UNITED STATES

SECURITIES AND EXCHANGE COMMISSIONWashington, DC 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

ObsEva SA

(Name of Issuer)

Common Stock

(Title of Class of Securities)

 H5861P103

(CINS Number)

January 25, 2017

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

☐ Rule 13d-1(b)

☒Rule 13d-1(c)

☐ Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CINS No. H5861P103  SCHEDULE 13G Page 2 of 8 Pages

1	NAME OF REPORTING PERSONS OrbiMed Capital GP V LLC
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) ☐ (b) ☐
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0
		6	SHARED VOTING POWER 2,559,931
		7	SOLE DISPOSITIVE POWER 0
		8	SHARED DISPOSITIVE POWER 2,559,931
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,559,931
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES			☐
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 8.64% *
12	TYPE OF REPORTING PERSON OO

* This percentage is based upon 29,631,262 shares of Common Stock, par value $0.001 per share (“Shares”), as set forth in the Issuer’s Final Prospectus, dated January 25, 2017, and filed with the Securities and Exchange Commission (“SEC”) on January 27, 2017. The number of Shares outstanding gives effect to the Issuer’s initial public offering and assumes no exercise by the underwriters option to purchase up to an additional 967,500 Shares.

CINS No. H5861P103  SCHEDULE 13G Page 3 of 8 Pages

1	NAME OF REPORTING PERSONS OrbiMed Advisors LLC
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) ☐ (b) ☐
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0
		6	SHARED VOTING POWER 2,559,931
		7	SOLE DISPOSITIVE POWER 0
		8	SHARED DISPOSITIVE POWER 2,559,931
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,559,931
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES			☐
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 8.64% *
12	TYPE OF REPORTING PERSON IA

* This percentage is based upon 29,631,262 shares of Common Stock, par value $0.001 per share (“Shares”), as set forth in the Issuer’s Final Prospectus, dated January 25, 2017, and filed with the Securities and Exchange Commission (“SEC”) on January 27, 2017. The number of Shares outstanding gives effect to the Issuer’s initial public offering and assumes no exercise by the underwriters option to purchase up to an additional 967,500 Shares.

CINS No. H5861P103  SCHEDULE 13G Page 4 of 8 Pages

1	NAME OF REPORTING PERSONS Samuel D. Isaly
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) ☐ (b) ☐
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0
		6	SHARED VOTING POWER 2,559,931
		7	SOLE DISPOSITIVE POWER 0
		8	SHARED DISPOSITIVE POWER 2,559,931
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,559,931
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES			☐
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 8.64% *
12	TYPE OF REPORTING PERSON IN

* This percentage is based upon 29,631,262 shares of Common Stock, par value $0.001 per share (“Shares”), as set forth in the Issuer’s Final Prospectus, dated January 25, 2017, and filed with the Securities and Exchange Commission (“SEC”) on January 27, 2017. The number of Shares outstanding gives effect to the Issuer’s initial public offering and assumes no exercise by the underwriters option to purchase up to an additional 967,500 Shares.

CINS No. H5861P103  SCHEDULE 13G Page 5 of 8 Pages

Item 1. (a) Name of Issuer:

ObsEva SA (the “Company”).

(b)  Address of Issuer’s Principal Executive Offices:

Chemin des Aulx, 12

1228 Plan-les-Ouates

Geneva, Switzerland

Item 2. (a) Name of Person Filing:

This Schedule 13G is being filed by each of the following persons (each a “Reporting Person”, and together, the “Reporting Persons”):

OrbiMed Capital GP V LLC (“GP V”)

OrbiMed Advisors LLC (“Advisors”)

Samuel D. Isaly (“Isaly”)

(b)  Address of Principal Business Office:

601 Lexington Avenue, 54th Floor

New York, NY 10022

(c)  Citizenship:

Please refer to Item 4 on each cover sheet for each filing person.

(d)  Title of Class of Securities:

Common Stock, par value $0.001 per share.

(e)  CINS No.:

H5861P103

CINS No. H5861P103  SCHEDULE 13G Page 6 of 8 Pages

Item 3.

Not Applicable

Item 4.  Ownership:

GP V is the sole general partner of OrbiMed Private Investments V, LP (“OPI V”), which holds 2,559,931 shares of Common Stock, par value $0.001 per share, of the Company (“Shares”). Advisors is an investment advisor in accordance with Rule 13d‑1(b)(1)(ii)(E) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and is the Managing Member of GP V. Isaly is the Managing Member of Advisors and a control person in accordance with Rule 13d-1(b)(1)(ii)(G) under the Exchange Act. On the basis of these relationships, GP V, Advisors and Isaly may be deemed to share beneficial ownership of the Shares held by OPI V.

(a) Amount beneficially owned: See the response(s) to Item 9 on the attached cover page(s).

(b) Percent of class: See the response(s) to Item 11 on the attached cover page(s).

(c) Number of shares as to which the person has:

(i) Sole power to vote or to direct the vote: See the response(s) to Item 5 on the attached cover page(s).

(ii) Shared power to vote or to direct the vote: See the response(s) to Item 6 on the attached cover page(s).

(iii) Sole power to dispose or to direct the disposition of: See the response(s) to Item 7 on the attached cover page(s).

(iv) Shared power to dispose or to direct the disposition of: See the response(s) to Item 8 on the attached cover page(s).

Item 5.  Ownership of Five Percent or Less of a Class.

Not Applicable.

Item 6.  Ownership of More Than Five Percent on Behalf of Another Person.

See Item 4.

Item 7. Identification and Classification of the Subsidiary which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.

Not Applicable.

CINS No. H5861P103  SCHEDULE 13G Page 7 of 8 Pages

Item 8. Identification and Classification of Members of the Group.

Not Applicable.

Item 9. Notice of Dissolution of Group.

Not Applicable.

Item 10. Certification.

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

CINS No. H5861P103  SCHEDULE 13G Page 8 of 8 Pages

SIGNATURES

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: February 3, 2017

ORBIMED ADVISORS LLC
By:	/s/ Samuel D. Isaly
	Name:	Samuel D. Isaly
	Title:	Managing Member
ORBIMED CAPITAL GP V LLC
By: OrbiMed Advisors LLC
Its Managing Member
By:	/s/ Samuel D. Isaly
	Name:	Samuel D. Isaly
	Title:	Managing Member
SAMUEL D. ISALY
	/s/ Samuel D. Isaly
	Name:	Samuel D. Isaly