Exhibit 5.1

	200 Clarendon Street
	Boston, Massachusetts  02116
	Tel: +1.617.948.6000  Fax: +1.617.948.6001
	www.lw.com
	FIRM / AFFILIATE OFFICES
	Austin	Moscow
	Beijing	Munich
	Boston	New York
	Brussels	Orange County
	Century City	Paris
	Chicago	Riyadh
	Dubai	San Diego
	Düsseldorf	San Francisco
	Frankfurt	Seoul
May 27, 2022	Hamburg	Shanghai
	Hong Kong	Silicon Valley
	Houston	Singapore
	London	Tel Aviv
	Los Angeles	Tokyo
BioXcel Therapeutics, Inc.	Madrid	Washington, D.C.
555 Long Wharf Drive	Milan

New Haven, Connecticut 06511

Re: Registration Statement on Form S-3; 278,520 shares of Common Stock, par value $0.001 per share

To the addressees set forth above:

We have acted as special counsel to BioXcel Therapeutics, Inc., a Delaware corporation (the “Company”), in connection with the registration for resale from time to time by the selling stockholders (the “Selling Stockholders”) named in the Prospectus (as defined below) of 278,520 shares (the “Shares”) of the Company’s common stock, $0.001 par value per share (“Common Stock”), issuable upon the exercise of warrants issued to the Selling Stockholders by the Company (the “Warrants”). The Shares are included in a registration statement on Form S-3 (the “Registration Statement”) under the Securities Act of 1933, as amended (the “Act”), and the related prospectus included in the Registration Statement (the “Prospectus”), filed with the Securities and Exchange Commission (the “Commission”) on May 27, 2022. This opinion is being furnished in connection with the requirements of Item 601(b)(5) of Regulation S-K under the Act, and no opinion is expressed herein as to any matter pertaining to the contents of the Registration Statement or the related Prospectus, other than as expressly stated herein with respect to the issue of the Shares.

As such counsel, we have examined such matters of fact and questions of law as we have considered appropriate for purposes of this letter. With your consent, we have relied upon certificates and other assurances of officers of the Company and others as to factual matters without having independently verified such factual matters. We are opining herein as to the General Corporation Law of the State of Delaware (the “DGCL”), and we express no opinion with respect to any other laws.

Subject to the foregoing and the other matters set forth herein, it is our opinion that, as of the date hereof, when the Shares shall have been duly registered on the books of the transfer agent and registrar therefor in the name or on behalf of the Selling Stockholders, and have been issued by the Company against payment therefor (not less than par value) in the circumstances contemplated by the Warrants, the issue of the Shares will have been duly authorized by all necessary corporate action of the Company and the Shares will be validly issued, fully paid and nonassessable.

May 27, 2022

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In rendering the foregoing opinion, we have assumed that: (i) the Company will comply with all applicable notice requirements regarding uncertificated shares provided in the DGCL; (ii) the Warrants have been duly executed and delivered by the Company and, under the internal laws of the State of New York, constitute valid and legally binding obligations of the Company; and (iii) upon the issue of any of the Shares, the total number of shares of Common Stock then issued and outstanding will not exceed the total number of shares of Common Stock that the Company is then authorized to issue under its certificate of incorporation and by the board of directors of the Company in connection with the offering contemplated by the Registration Statement.

This opinion is for your benefit in connection with the Registration Statement and may be relied upon by you and by persons entitled to rely upon it pursuant to the applicable provisions of the Act. We consent to your filing this opinion as an exhibit to the Registration Statement and to the reference to our firm in the Prospectus under the heading “Legal Matters.” In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the Commission thereunder.

Sincerely,

/s/ LATHAM & WATKINS LLP

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