Exhibit 5.1

                               LATHROP & GAGE L.C.
                                   LAW OFFICES
2345 Grand Boulevard                                     1050/40 Corporate Woods
Suite 2800                                             9401 Indian Creek Parkway
Kansas City, Missouri 64108-2684                Overland Park, Kansas 66210-2007
816-292-2000, Fax 816-292-2001                    913-451-5100, Fax 913-451-0875

                                 JOHN H. CALVERT
                                  816-460-5807
                            jcalvert@lathropgage.com

                                  June 18, 1999

Board of Directors
Lab Holdings, Inc.
5000 West 95th Street
Shawnee Mission, Kansas 66207

     Re:  Offering by Lab  Holdings,  Inc.  (the  "Company") of shares of Common
Stock,  $0.01 par value (the "Common Stock") pursuant to that certain  Agreement
and Plan of Merger by and between Lab Holdings, Inc. and LabOne, Inc. as amended
and  restated,  dated as of March 7, 1999 (the  "Merger  Agreement"),  a copy of
which is appended to the Joint  Proxy  Statement/Prospectus  that has been filed
with  the  Securities  and  Exchange  Commission  as a part of the  registration
statement  of the Company on Form S-4,  file No.  333-76131 (the  "Registration
Statement").

Gentlemen,

         We have acted as counsel to the  Company in  connection  with the above
referenced  Offering  pursuant to which the Company  proposes to issue shares of
its Common  Stock to the holders of common stock of LabOne,  Inc. in  accordance
with the terms of the Merger Agreement.

         We have examined the Merger  Agreement,  the Articles of  Incorporation
and Bylaws of the Company, as amended, the proceedings of the Board of Directors
of the Company in connection with the  authorization,  execution and delivery of
the Merger Agreement and the filing of the Registration Statement,  certificates
of officers of the Company and of state officials and such other documents as we
have deemed  necessary  in order to express  the  opinion set out herein.  As to
certain questions of fact material to our opinion we have,  without  independent
investigation,  relied upon the representations and warranties of the parties as
set forth in the Merger  Agreement.  We have also assumed the genuineness of all
signatures on original documents and certificates examined by us.

         Our opinion is limited to the matters  expressly set forth herein,  and
no opinion is to be implied or may be inferred  beyond the matters  expressly so
stated.  Our  opinion is also



Board of Directors
Lab Holdings, Inc.
June 18, 1999
Page 2

limited to the effect of the laws of the state of Missouri  and the Federal
laws of the United  States.  We express no opinion with respect to the effect of
the laws of any other jurisdiction on the matters referred to herein. We further
disclaim any obligation to update this opinion letter for events occurring after
the date of this opinion letter.

         Based upon the foregoing, and assuming that (i) the Merger Agreement is
approved by the holders of the  requisite  number of shares of capital  stock of
the parties thereto, (ii) that all conditions to the Merger Agreement, including
that the  Articles  Amendment  has become  effective,  are either  satisfied  or
properly waived,  and (iii) that the Merger Agreement is properly filed with and
certificates  of merger with respect  thereto are duly issued by the Secretaries
of State of Missouri and Delaware,  all as contemplated by the Merger Agreement,
we are of the opinion that the Common Stock,  when issued to the stockholders of
LabOne  pursuant  to the  Merger  Agreement,  will be duly  authorized,  legally
issued, fully paid and non-assessable.

         We  consent  to  the  filing  of  this  opinion  as an  exhibit  to the
Registration  Statement.  We also  consent to the use of this opinion and to the
reference to our firm under the caption  ("Legal  Opinions")  in the Joint Proxy
Statement/Prospectus  of the Registration  Statement and amendments  thereto. 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.



                                           Very truly yours,

                                           LATHROP & GAGE L.C.


                                       By:  S/John H. Calvert
                                           John H. Calvert