[LETTERHEAD OF KAYE SCHOLER LLP]             Exhibit 5.1


                                                   425 Park Avenue
                                                   New York, New York 10022-3598
                                                   212 836-8000
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                                                   www.kayescholer.com

                                December 14, 2005

Emergency Medical Services Corporation
6200 S. Syracuse Way
Greenwood Village, CO  80111

            Re:   Emergency Medical Services Corporation
                  Registration Statement on Form S-1
                  Registration No. 333-127115

Ladies and Gentlemen:

      This opinion is furnished to you in connection with a registration
statement on Form S-1 (the "REGISTRATION STATEMENT"), filed with the Securities
and Exchange Commission (the "COMMISSION") under the Securities Act of 1933, as
amended (the "SECURITIES ACT"), for the registration of 10,118,325 shares of
class A common stock, par value $0.01 per share (the "SHARES"), of Emergency
Medical Services Corporation, a Delaware corporation (the "COMPANY"). The Shares
consist of (i) 8,970,000 Shares to be sold pursuant to an underwriting agreement
to be entered into among the Company, Banc of America Securities LLC, and J.P.
Morgan Securities Inc., as Representatives, and the Selling Stockholders
signatory thereto (in the form filed as Exhibit 1.1 to the Registration
Statement, the "UNDERWRITING AGREEMENT"), including (a) 7,800,000 Shares to be
sold by the Company (the "COMPANY SHARES") and (b) up to 1,170,000 Shares to be
sold by certain selling stockholders (the "STOCKHOLDER SHARES") if the
underwriters exercise their over-allotment option and (ii) 1,148,325 Shares to
be issued in exchange for class B units (the "PARTNERSHIP UNITS") representing
limited partnership interests of Emergency Medical Services L.P. (the "EXCHANGE
SHARES").

      We have acted as counsel for the Company in connection with its proposed
issuance and sale of the Shares. In rendering the opinion set forth below, we
have examined originals or copies, certified or otherwise identified to our
satisfaction, of such documents, corporate records, certificates of public
officials and other instruments as we have deemed necessary or advisable for the
purpose of rendering this opinion.

      The law covered by this opinion is limited to the General Corporation Law
of the State of Delaware.

      Based on and subject to the foregoing, it is our opinion that, upon the
filing of the Amended and Restated Certificate of Incorporation of the Company
in the form filed as Exhibit 3.1 to the Registration Statement and the execution
and delivery of the Underwriting Agreement, (the "CERTIFICATE OF INCORPORATION")
with the Secretary of State of the State of Delaware, the Shares will be duly
authorized, and the Shares will be validly issued, fully paid and non-assessable
as follows:

      (1) in the case of the Company Shares, when the Company Shares have been
issued and sold by the Company and the Company has received the purchase price
therefor, in

Emergency Medical Services Corporation  2                      December 14, 2005

accordance with the terms of the Underwriting Agreement;

      (2) in the case of the Stockholder Shares, when the Stockholder Shares
have been issued upon conversion of the same number of shares of the Company's
Class B Common Stock, in accordance with the terms of the Certificate of
Incorporation; and

      (3) in the case of the Exchange Shares, when the Exchange Shares have been
issued by the Company and the Company has received one Partnership Unit for each
Exchange Share, in accordance with the terms of the form of Amendment to the
Agreement of Limited Partnership of Emergency Medical Services L.P. included as
Exhibit 3.4.2 to the Registration Statement.

      We hereby consent to the use of this opinion as Exhibit 5.1 to the
Registration Statement and to the reference to this firm under the caption
"Legal Matters" therein. In giving this opinion, we do not thereby admit that we
are within the category of persons whose consent is required under Section 7 of
the Securities Act or the rules and regulations of the Securities and Exchange
Commission thereunder.

                                        Very truly yours,

                                        /s/ Kaye Scholer LLP