Exhibit

Exhibit 5.1

[Letterhead of Stinson Leonard Street LLP]

May 9, 2017

DST Systems, Inc.

333 West 11th Street

Kansas City, Missouri 64105

Re: DST Systems, Inc., Registration Statement on Form S-3

Ladies and Gentlemen:

We have acted as counsel to DST Systems, Inc., a Delaware corporation (the “Company”), in connection with the automatic shelf registration statement on Form S-3, to be filed on the date hereof by the Company (the “Registration Statement”) with the U.S. Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Act”). The Registration Statement relates to the issuance and sale from time to time by the Company, pursuant to Rule 415 of the General Rules and Regulations promulgated under the Act, of the following securities of the Company: (i) shares of common stock, $0.01 par value per share (the “Common Stock”); (ii) shares of preferred stock, $0.01 par value per share (the “Preferred Stock”), in one or more series; (iii) debt securities (the “Debt Securities”) which may be issued in one or more series under one or more indentures (each, an “Indenture” and, collectively, “Indentures”), entered into or proposed to be entered into between the Company and the trustee to be named therein (the “Trustee”); (iv) warrants (the “Warrants”) to purchase Debt Securities, shares of Common Stock or Preferred Stock or other securities pursuant to one or more warrant agreements (each, a “Warrant Agreement”) proposed to be entered into between the Company and warrant agents to be named therein (each, a “Warrant Agent” and, collectively, “Warrant Agents”); (v) purchase contracts (the "Purchase Contracts"), which may be issued separately or as part of units consisting of a purchase contract and other securities or obligations issued by the Company or third parties; (vi) units (the "Units") comprised of one or more of the other securities that may be offered under the Shelf Registration Statement, in any combination; (vii) subscription rights (the "Subscription Rights") to purchase Common Stock or other securities of the Company; as well as such indeterminate number of shares of Common Stock or Preferred Stock and amount of Debt Securities and Warrants, as may be issued upon conversion, exchange or exercise of any Preferred Stock, Debt Securities, Warrants, Purchase Contracts, Units, or Subscription Rights, including such shares of Common Stock or Preferred Stock or amounts of other securities as may be issued pursuant to anti-dilution adjustments, in amounts, at prices and on terms to be determined at the time of offering (collectively, "Indeterminate Securities"). The Registration Statement also relates to the sale of the Company’s Common Stock from time to time by certain stockholders of the Company to be named in a prospectus supplement (the “Selling Stockholders”), pursuant to Rule 415 of the General Rules and Regulations promulgated under the Act (the “Secondary Shares”). The Common Stock, Preferred Stock, Debt Securities, Warrants, Purchase Contracts, Units, Subscription Rights, Indeterminate Securities and Secondary Shares are collectively referred to herein as the “Offered Securities.”

This opinion is being delivered in accordance with the requirements of Item 601(b)(5) of Regulation S-K under the Act.

In connection with this opinion, we have examined originals or copies, certified or otherwise identified to our satisfaction, of:

(i) the Registration Statement relating to the Offered Securities;

(ii) the Amended and Restated Certificate of Incorporation of the Company, as amended, as certified by the Secretary of the State of Delaware (the “Certificate of Incorporation”);

(iii) the Amended and Restated Bylaws of the Company, as currently in effect, as certified by the Secretary of the Company (the “Bylaws”);

(iv) the Indenture relating to Debt Securities (the “Indenture”) and the form of note included therein, to be filed as Exhibit 4.2 to the Registration Statement; and

(v) certain resolutions of the Board of Directors of the Company (the “Board of Directors”) relating to the registration of the Offered Securities, including, but not limited to, the resolutions of the Board of Directors approved on May 9, 2017.

We have also examined originals or copies, certified or otherwise identified to our satisfaction, of such records of the Company and such agreements, certificates and receipts of public officials, certificates of officers or other representatives of the Company and others, and such other documents, certificates and records as we have deemed necessary or appropriate as a basis for the opinions set forth herein.

In our examination, we have assumed the legal capacity of all natural persons, the genuineness of all signatures, including endorsements, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as facsimile, electronic, certified, conformed or photostatic copies, and the authenticity of the originals of such copies. As to any facts relevant to the opinions expressed herein which were not independently established or verified, we have relied upon oral or written statements and representations of officers and other representatives of the Company and others and of public officials. In making our examination of documents executed or to be executed, we have assumed that the parties thereto, other than the Company, had or will have the power, corporate or other, to enter into and perform all obligations thereunder and have also assumed the due authorization by all requisite action, corporate or other, and the execution and delivery by such parties of such documents, and the validity and binding effect thereof on such parties. We have also assumed that the Indenture and the Warrant Agreements will be duly authorized, executed and delivered by the Trustee and the Warrant Agents, as the case may be, and, in the case of the Indenture, in substantially the form reviewed by us, and that any Debt Securities or Warrants, that may be issued will be manually authenticated, signed or countersigned, as the case may be, by duly authorized officers of the applicable Warrant Agent or the Trustee, as the case may be and that each will be governed by the laws of the State of New York.

In addition, we have assumed that the terms of the Offered Securities of the Company will have been established so as not to, and that the execution and delivery by the Company of, and the performance of its obligations under, the Indenture, the Offered Securities of the Company and the Warrant Agreements, will not violate, conflict with or constitute a default under (i) any agreement or instrument to which the Company or its properties are subject, (ii) any law, rule or regulation to which the Company or its properties is subject, (iii) any judicial or regulatory order or decree of any governmental authority or (iv) any consent, approval, license, authorization or validation of, or filing, recording or registration with, any governmental authority. In rendering the opinion set forth in paragraph 8 below, we have assumed that (i) the Company has received or will receive the entire amount of the consideration contemplated by the Board of Directors authorizing the issuance of such Secondary Shares and (ii) such consideration was not nor will not be less than $0.01 per Secondary Share, and we have further assumed that (i) the Board of Directors, including any appropriate committee appointed thereby, and appropriate officers of the Company has taken or will take all necessary corporate action to approve the issuance of the Secondary Shares and related matters; (ii) the terms of the issuance and sale of the Secondary Shares have been or will be duly established and in conformity with the Certificate of Incorporation and Bylaws so as not to violate any applicable law, the Certificate of Incorporation or By-laws or result in a default under or breach of any agreement or instrument binding upon the Company and so as to comply with any requirement or restriction imposed by any court or governmental body having jurisdiction over the Company; (iii) if certificated, certificates in the form required under Delaware corporate law representing the Secondary Shares will be duly executed and countersigned; and (iv) the Secondary Shares will be registered in the Company’s share registry and delivered upon payment of the agreed-upon consideration therefore. As to any facts material to the opinions expressed herein which were not independently established or verified, we have relied upon oral or written statements and representations of officers and other representatives of the Company and others.

Our opinions set forth herein are limited to (i) the General Corporation Law of the State of Delaware and (ii) the laws of the State of New York that, in our experience, are normally applicable to securities of the type contemplated by the Registration Statement and, to the extent that judicial or regulatory orders or decrees or consents, approvals, licenses, authorizations, validations, filings, recordings or registrations with governmental authorities are relevant, to those required under such laws (all of the foregoing being referred to as “Opined on Law”). We do not express any opinion as to any non-Opined on Law on the opinions herein stated. The Offered Securities may be issued from time to time on a delayed or continuous basis, and this opinion is limited to the laws, including the rules and regulations, as in effect on the date hereof, which laws are subject to change with possible retroactive effect.

Based upon the foregoing and subject to the limitations, qualifications, exceptions and assumptions set forth herein, we are of the opinion that:

With respect to the shares of any Common Stock offered by the Company, including any Indeterminate Securities (the “Offered Common Stock”), when (i) an appropriate prospectus supplement with respect to the Offered Common Stock has been prepared, delivered and filed in compliance with the Act and the applicable rules and regulations thereunder; (ii) if the Offered Common Stock is to be sold pursuant to a firm commitment underwritten offering, the underwriting agreement with respect to the Offered Common Stock has been duly authorized, executed and delivered by the Company and the other parties thereto; (iii) the Board of Directors of the Company, including any appropriate committee appointed thereby, and appropriate officers of the Company have taken all necessary corporate action to approve the issuance of the Offered Common Stock and related matters; (iv) terms of the issuance and sale of the Offered Common Stock have been duly established and are then in conformity with the Certificate of Incorporation and Bylaws so as not to violate any applicable law, the Certificate of Incorporation or Bylaws; (v) if certificated, certificates in the form required under Delaware corporate law representing the shares of Offered Common Stock are duly executed and countersigned; and (vi) the shares of Offered Common Stock are registered in the Company’s share registry and delivered upon payment of the agreed-upon consideration therefore, the shares of Offered Common Stock (including any Common Stock duly issued upon conversion, exchange or exercise of any Preferred Stock, Debt Securities, Warrants, Purchase Contracts, Units, or Subscription Rights), when issued and sold in accordance with the applicable underwriting agreement, if any, or any other duly authorized, executed and delivered valid and binding agreement, will be duly authorized, validly issued, fully paid and nonassessable, provided that the consideration therefor is not less than $0.01 per share of Common Stock.

With respect to the shares of any series of Preferred Stock offered by the Company, including any Indeterminate Securities (the “Offered Preferred Stock”), when (i) an appropriate prospectus supplement with respect to the Offered Preferred Stock has been prepared, delivered and filed in compliance with the Act and the applicable rules and regulations thereunder; (ii) if the Offered Preferred Stock is to be sold pursuant to a firm commitment underwritten offering, the underwriting agreement with respect to the Offered Preferred Stock has been duly authorized, executed and delivered by the Company and the other parties thereto; (iii) the Board of Directors of the Company, including any appropriate committee appointed thereby, and appropriate officers of the Company have taken all necessary corporate action to approve the issuance, sale and terms of the Offered Preferred Stock and related matters, including the adoption of a Certificate of Designation for the Offered Preferred Stock in accordance with the applicable provisions of the corporate laws of the State of Delaware (the “Certificate of Designation”); (iv) the filing of the Certificate of Designation with the Secretary of State of the State of Delaware has duly occurred; (v) the terms of the Offered Preferred Stock and of their issuance and sale have been duly established and are then in conformity with the Certificate of Incorporation, including the Certificate of Designation relating to the Offered Preferred Stock, and the Bylaws of the Company so as not to violate any applicable law, the Certificate of Incorporation or Bylaws; (vi) if certificated, certificates in the form required under Delaware corporate law representing the shares of Offered Preferred Stock are duly executed and countersigned; and (vii) the shares of Offered Preferred Stock are registered in the Company’s share registry and delivered upon payment of the agreed-upon consideration therefore, the shares of the Offered Preferred Stock (including any Preferred Stock duly issued upon conversion, exchange or exercise of any Preferred Stock, Debt Securities, Warrants, Purchase Contracts, Units, or Subscription Rights), when issued and sold in accordance with the applicable underwriting agreement, if any, or any other duly authorized, executed and delivered valid and binding agreement, will be duly authorized, validly issued, fully paid and nonassessable, provided that the consideration therefor is not less than $0.01 per share of Preferred Stock.

With respect to any series of Debt Securities offered by the Company, including any Indeterminate Securities (the “Offered Debt Securities”), when (i) the Indenture has been qualified under the Trust Indenture Act of 1933, as amended; (ii) an appropriate prospectus supplement with respect to any Offered Debt Securities has been prepared, delivered and filed in compliance with the Act and the applicable rules and regulations thereunder; (iii) if the Offered Debt Securities are to be sold pursuant to a firm commitment underwritten offering, the underwriting agreement with respect to the Offered Debt Securities has been duly authorized, executed and delivered by the Company and the other parties thereto; (iv) the Indenture has been duly authorized, executed and delivered by the Company and the other parties thereto; (v) the Board of Directors of the Company, including any appropriate committee appointed thereby, and appropriate officers of the Company have taken all necessary corporate action to approve the issuance, sale and terms of the Offered Debt Securities and related matters; (vi) the terms of the Offered Debt Securities and of their issuance and sale have been duly established in conformity with the Indenture so as not to violate any applicable law, the Certificate of Incorporation or Bylaws; and (vii) the Offered Debt Securities, in the form to be filed on a Current Report on Form 8-K or other applicable periodic report in the manner contemplated in the Registration Statement or any prospectus supplement relating thereto, have been duly executed and authenticated in accordance with the provisions of the Indenture and duly delivered to the purchasers thereof upon payment of the agreed-upon consideration therefor, the Offered Debt Securities (including any Debt Securities duly issued upon conversion, exchange or exercise of any Preferred Stock, Debt Securities, Warrants, Purchase Contracts, Units, or

Subscription Rights), when issued and sold in accordance with the applicable Indenture and the applicable underwriting agreement, if any, or any other duly authorized, executed and delivered valid and binding agreement, will be valid and binding obligations of the Company, enforceable against the Company in accordance with their respective terms, except to the extent that enforcement thereof may be limited by (a) bankruptcy, insolvency, reorganization, fraudulent conveyance, moratorium or other similar laws now or hereafter in effect relating to creditors’ rights generally, (b) general principles of equity (regardless of whether enforceability is considered in a proceeding at law or in equity), (c) public policy considerations which may limit the rights of parties to obtain remedies, (d) the waivers of any usury defense contained in the Indenture or Offered Debt Securities which may be unenforceable, (e) requirements that a claim with respect to any Offered Debt Securities denominated in a currency, currency unit or composite currency other than United States dollars (or a judgment denominated other than in United States dollars in respect of such claim) be converted into United States dollars at a rate of exchange prevailing on a date determined pursuant to applicable law and (f) governmental authority to limit, delay or prohibit the making of payments outside the United States or in foreign currencies, currency units or composite currencies.

With respect to any Warrants offered by the Company, including any Indeterminate Securities (the “Offered Warrants”), when (i) an appropriate prospectus supplement with respect to the Offered Warrants has been prepared, delivered and filed in compliance with the Act and the applicable rules and regulations thereunder; (ii) if the Offered Warrants are to be sold pursuant to a firm commitment underwritten offering, the underwriting agreement with respect to the Offered Warrants has been duly authorized, executed and delivered by the Company and the other parties thereto; (iii) the Board of Directors of the Company, including any appropriate committee appointed thereby, and appropriate officers of the Company have taken all necessary corporate action to approve the issuance and terms of the Offered Warrants and the Offered Securities of the Company into which the Offered Warrants are exercisable, the consideration to be received therefor and related matters; (iv) a Warrant Agreement relating to the Offered Warrants has been duly authorized, executed and delivered by the Company and the other parties thereto; (v) the terms of the Offered Warrants and of their issuance and sale have been duly established in conformity with the applicable Warrant Agreement so as not to violate any applicable law, the Certificate of Incorporation or Bylaws; and (vi) the Offered Warrants, in the form to be filed on a Current Report on Form 8-K or other applicable periodic report in the manner contemplated in the Registration Statement or any prospectus supplement relating thereto, have been duly executed, delivered and countersigned in accordance with the provisions of the applicable Warrant Agreement and duly issued and sold in the applicable form to be filed as an exhibit to the Registration Statement or any amendment thereto and in the manner contemplated in the Registration Statement or any prospectus supplement or term sheet relating thereto, the Offered Warrants, when issued and sold in accordance with the applicable Warrant Agreement and the applicable underwriting agreement or any other duly authorized, executed and delivered valid and binding agreement, will be duly authorized and validly issued and will constitute valid and binding obligations of the Company, enforceable against the Company in accordance with their respective terms, except to the extent that enforcement thereof may be limited by (a) bankruptcy, insolvency, reorganization, fraudulent conveyance, moratorium or other similar laws now or hereafter in effect relating to creditors’ rights generally, (b) general principles of equity (regardless of whether enforceability is considered in a proceeding at law or in equity) and (c) public policy considerations which may limit the rights of parties to obtain remedies.

With respect to any Purchase Contracts to be offered by the Company pursuant to the Registration Statement, including any Indeterminate Securities constituting Purchase Contracts (the “Offered Purchase Contracts”), when (i) an appropriate prospectus supplement or term sheet with respect to the Offered Purchase Contracts has been prepared, delivered and filed in compliance with the Act and the applicable rules and regulations thereunder, (ii) if the Offered Purchase Contracts are to be sold pursuant to a firm commitment underwritten offering, the underwriting agreement with respect to the Offered Purchase Contracts has been duly authorized, executed and delivered by the Company and the other parties thereto, (iii) the Board of Directors, including any appropriate committee appointed thereby, and appropriate officers of the Company have taken all necessary corporate action to approve the issuance and terms of the Offered Purchase Contracts and related matters, (iv) a Purchase Contract Agreement relating to the Offered Purchase Contracts has been duly authorized, executed and delivered by each party thereto, (v) the terms of the Offered Purchase Contracts and of their issuance and sale have been duly established in conformity with the applicable Purchase Contract Agreement so as not to violate any applicable law, the Certificate or the Bylaws or result in a default under or breach of any agreement or instrument binding upon the Company and so as to comply with any requirement or restriction imposed by any court or governmental body having jurisdiction over the Company and the applicable Purchase Contract Agent, (vi) the securities relating to such Offered Purchase Contracts have been duly authorized for issuance and (vii) the applicable Offered Purchase Contracts have been duly executed, delivered, countersigned, issued and sold in accordance with the provisions of the applicable Purchase Contract Agreement to be filed on a Current Report on Form 8-K or other applicable periodic report in the manner contemplated in the Registration Statement or any prospectus supplement or term sheet relating thereto, the Offered Purchase Contracts,

when issued and sold in accordance with the applicable Purchase Contract Agreement and the applicable underwriting agreement, if any, or any other duly authorized, executed and delivered valid and binding purchase or agency agreement, will be valid and binding obligations of the Company, enforceable against the Company in accordance with their respective terms, except to the extent that enforcement thereof may be limited by (a) bankruptcy, insolvency, reorganization, fraudulent conveyance, moratorium or other similar laws now or hereafter in effect relating to creditors’ rights generally, (b) general principles of equity (regardless of whether enforceability is considered in a proceeding at law or in equity) and (c) public policy considerations which may limit the rights of parties to obtain remedies.

With respect to any Units to be offered by the Company pursuant to the Registration Statement, including any Indeterminate Securities constituting Units (the “Offered Units”), when (i) an appropriate prospectus supplement or term sheet with respect to the Offered Units has been prepared, delivered and filed in compliance with the Act and the applicable rules and regulations thereunder, (ii) if the Offered Units are to be sold pursuant to a firm commitment underwritten offering, the underwriting agreement with respect to the Offered Units has been duly authorized, executed and delivered by the Company and the other parties thereto, (iii) the Board of Directors, including any appropriate committee appointed thereby, and appropriate officers of the Company have taken all necessary corporate action to approve the issuance and terms of the Offered Units and related matters, (iv) the terms of the Offered Units and of their issuance and sale have been duly established in conformity with the applicable Stock Purchase Contract Agreement so as not to violate any applicable law, the Certificate or the Bylaws or result in a default under or breach of any agreement or instrument binding upon the Company and so as to comply with any requirement or restriction imposed by any court or governmental body having jurisdiction over the Company and the applicable Stock Purchase Contract Agent, (v) any Stock Purchase Contracts and Debt Securities or debt obligations of third parties, including U.S. Treasury securities, or other securities (or any combination of the foregoing) included in such Offered Stock Purchase Units have been duly issued and paid for in the manner contemplated in the Registration Statement and any prospectus supplement or term sheet relating thereto, (vi) the securities relating to such Offered Stock Purchase Units have been duly authorized for issuance and have been duly issued and paid for in the manner contemplated in the Registration Statement or any prospectus supplement or term sheet relating thereto and (vii) the applicable Offered Units have been duly executed, delivered, countersigned, issued and sold in accordance with the provisions of any applicable collateral arrangement to be filed on a Current Report on Form 8-K or other applicable periodic report in the manner contemplated in the Registration Statement or any prospectus supplement or term sheet relating thereto, the Offered Units, when issued and sold in accordance with any applicable collateral arrangement and the applicable underwriting agreement, if any, or any other duly authorized, executed and delivered valid and binding purchase or agency agreement, will be valid and binding obligations of the Company, enforceable against the Company in accordance with their respective terms, except to the extent that enforcement thereof may be limited by (a) bankruptcy, insolvency, reorganization, fraudulent conveyance, moratorium or other similar laws now or hereafter in effect relating to creditors’ rights generally, (b) general principles of equity (regardless of whether enforceability is considered in a proceeding at law or in equity) and (c) public policy considerations which may limit the rights of parties to obtain remedies.

With respect to any Subscription Rights to be offered by the Company pursuant to the Registration Statement, including any Indeterminate Securities constituting Subscription Rights (the “Offered Subscription Rights”), when (i) an appropriate prospectus supplement or term sheet with respect to the Offered Subscription Rights has been prepared, delivered and filed in compliance with the Act and the applicable rules and regulations thereunder, (ii) if the Offered Subscription Rights are to be sold pursuant to a firm commitment underwritten offering, the underwriting agreement with respect to the Offered Subscription Rights has been duly authorized, executed and delivered by the Company and the other parties thereto, (iii) the Board of Directors, including any appropriate committee appointed thereby, and appropriate officers of the Company have taken all necessary corporate action to approve the issuance and terms of the Offered Subscription Rights, the Subscription Rights Agreement and related matters, including setting forth the terms of the Subscription Rights in a Subscription Rights Certificate, if applicable, (iv) a Subscription Rights Agreement relating to the Offered Subscription Rights has been duly authorized, executed and delivered by each party thereto, (v) the terms of the Offered Subscription Rights and of their issuance and sale have been duly established in conformity with the applicable Subscription Rights Agreement and Subscription Rights Certificate so as not to violate any applicable law, the Certificate or the Bylaws or result in a default under or breach of any agreement or instrument binding upon the Company and so as to comply with any requirement or restriction imposed by any court or governmental body having jurisdiction over the Company and the applicable Subscription Agent, (vi) the securities relating to such Offered Subscription Rights have been duly authorized for issuance, and (vii) the Offered Subscription Rights have been duly executed, delivered, countersigned, issued and sold in accordance with the provisions of the applicable Subscription Rights Agreement and Subscription Rights Certificate to be filed on a Current Report on Form 8-K or other applicable periodic report in the manner contemplated in the Registration

Statement or any prospectus supplement or term sheet relating thereto, the Offered Subscription Rights, when issued and sold in accordance with the applicable Subscription Rights Agreement and Subscription Rights Certificate and the applicable underwriting agreement, if any, or any other duly authorized, executed and delivered valid and binding purchase or agency agreement, will be valid and binding obligations of the Company, enforceable against the Company in accordance with their respective terms, except to the extent that enforcement thereof may be limited by (a) bankruptcy, insolvency, reorganization, fraudulent conveyance, moratorium or other similar laws now or hereafter in effect relating to creditors’ rights generally, (b) general principles of equity (regardless of whether enforceability is considered in a proceeding at law or in equity) and (c) public policy considerations which may limit the rights of parties to obtain remedies.


8.	With respect to any Secondary Shares to be offered by the Selling Stockholders, such Secondary Shares have been duly authorized, validly issued and are fully paid and nonassessable.

We hereby consent to the filing of this opinion with the Commission as an exhibit to the Registration Statement. We also hereby consent to the use of our name under the heading “Legal Matters” in the prospectus which forms a part of the Registration Statement. In giving this consent, we do not thereby admit that we are within the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the Commission promulgated thereunder. This opinion is expressed as of the date hereof unless otherwise expressly stated, and we disclaim any undertaking to advise you of any subsequent changes in the facts stated or assumed herein or of any subsequent changes in applicable laws.



	Very truly yours,

	/s/ Stinson Leonard Street LLP