
<PAGE>




                                                           Exhibit 5


                      [McDermott, Will & Emery Letterhead]


                                                                August 11, 1999


Alternative Resources Corporation
100 Tri-State International
Suite 300
Lincolnshire, IL 60069

Dear Ladies and Gentlemen:

     We have acted as counsel for Alternative Resources Corporation (the
"Company") in connection with the preparation and filing of a Registration
Statement on Form S-8 (the "Registration Statement") for the registration
under the Securities Act of 1933, as amended, of 700,000 shares of the
Company's Common Stock, $.01 par value (the "Common Stock"), which may be
issued pursuant to certain non-qualified stock options (the "Option
Agreements") constituting the Alternative Resources Corporation Key Employee
Stock Option Plan (the "Plan").

     We have examined or considered:

     1.       A copy of the Company's Amended and Restated Certificate of
              Incorporation;

     2.       A copy of the Amended and Restated By-Laws of the Company;

     3.       Copies of resolutions duly adopted by the Board of Directors
              of the Company relating to the Option Agreements; and

     4.       Copies of the Option Agreements constituting the Plan.

        In addition to the examination outlined above, we have conferred with
various officers of the Company and have ascertained or verified, to our
satisfaction, such additional facts as we deemed necessary or appropriate for
the purposes of this opinion.

        We are of the opinion that the Common Stock, when issued pursuant to
and in accordance with the terms of the respective Option Agreements and
against payment of the purchase price provided for therein, will be legally
issued, fully paid and nonassessable.

        We hereby consent to the reference to our firm in the Registration
Statement and to the filing of this opinion by the Company as an Exhibit to
the Registration Statement.

                                Yours very truly,


                                /s/ McDermott, Will & Emery



