Exhibit 5.1

Baker McKenzie Switzerland AG Holbeinstrasse 30 P.O. Box 8034 Zurich Switzerland   T +41 44 384 14 14 F +41 44 384 12 84 zurich.info@bakermckenzie.com www.bakermckenzie.com

Zurich, June [●], 2025 | MC/jor

NLS Pharmaceutics Ltd – Registration Statement on Form F-4

Ladies and Gentlemen,

We have acted as special Swiss counsel to NLS Pharmaceutics Ltd., a stock corporation incorporated under the laws of Switzerland (the “Company”), in connection with the filing of a Registration Statement on Form F-4, filed on or around the date hereof (the “Registration Statement”), including the accompanying prospectus set forth therein, with the United States Securities and Exchange Commission (the “SEC”) for the purpose of registering under the United States Securities Act of 1933, as amended (the “Securities Act”), in connection with the issuance by the Company of (i) [●]common shares of the Company, par value CHF 0.03 per share (the “Common Shares”); and (ii) [●] Common Shares issuable upon exercise of pre-funded warrants (the Ordinary Shares underlying the pre-funded warrants,the “Warrant Shares”), in each case, to be issued pursuant to the merger (the “Merger”) contemplated by the Agreement and Plan of Merger, dated as of November 4, 2024 and as amended on January 30, 2025, February 17, 2025, May 5, 2025 and June 5, 2025, by and among the Company, NLS Pharmaceutics (Israel) Ltd., an Israeli company and a wholly owned subsidiary of the Company (the “Merger Sub”), and Kadimastem Ltd., an Israeli publicly traded company limited by shares (TASE: KDST) (“Kadimastem”) (the “Merger Agreement”). As such counsel, we have been requested to give our opinion as to certain legal matters of Swiss law.

This opinion is confined to and given on the basis of the laws of Switzerland in force at the date hereof. Such laws and the interpretation thereof are subject to change. In the absence of explicit statutory law, we base our opinion solely on our independent professional judgment. This opinion is also confined to the matters stated herein and is not to be read as extending, by implication or otherwise, to any other matter.

For purposes of this opinion we have not conducted any due diligence or similar investigation as to factual circumstances, which are or may be referred to in the Documents (as defined hereafter), and we express no opinion as to the accuracy of representations and warranties of facts set out in the Documents or the factual background assumed therein.

For purposes of this opinion, we have only reviewed originals or copies of the following documents (collectively the “Documents”):

No documents, other than the Documents, have been reviewed by us in connection with this opinion.

In rendering the opinion below, we assumed:

Based upon the foregoing and subject to the qualifications set out below, we are of the opinion that subject to and effective upon the Merger, and upon receipt by the Company of the consideration for the issuance of the Ordinary Shares or Warrant Shares, as applicable, contemplated under the Merger Agreement:

This opinion is subject to the following qualifications:

In this opinion, Swiss legal concepts are expressed in English terms and not in their original Swiss language. The concepts concerned may not be identical to the concepts described by the same English terms as they exist under the laws of other jurisdictions. This opinion may, therefore, only be relied upon under the express condition that any issues of interpretation or liability arising hereunder will be governed by Swiss law and that any dispute arising out of or in connection with this opinion shall be subject to the exclusive jurisdiction of Zurich 1, Switzerland.

This opinion is given as of the date hereof. We have no responsibility to notify you of changes of law or facts affecting the opinions expressed herein that occur or come to our attention after the date hereof.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and further consent to the reference to our name under the caption “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 Securities Act.

Yours faithfully,

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