DORA MER, LAW OFFICE
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124, IBN GVIROL STREET
TEL AVIV 62038, ISRAEL
TEL: 972-3-5277773, 5276771
FAX:  972-3-5275999
                             E-mail: doram@mer.co.il


                                                                       EXHIBIT 5


                                            March 14 , 2005

Mer Telemanagement Solutions Ltd.
22 Zarhin Street
Ra'anana 43662
Israel

Ladies and Gentlemen:

     We  refer to the  Registration  Statement  on Form  S-8 (the  "Registration
Statement") to be filed with the Securities  and Exchange  Commission  under the
Securities  Act of 1933,  as amended (the  "Securities  Act"),  on behalf of Mer
Telemanagement  Solutions  Ltd.  (the  "Company"),  relating  to  893,915 of the
Company's  Ordinary  Shares,  NIS 0.01 nominal  value per share (the  "Shares"),
issuable  upon the exercise of options  granted or to be granted  under the 2003
Israeli Share Option Plan (collectively, the "Plan").

     We are members of the Israel Bar and we express no opinion as to any matter
relating to the laws of any jurisdiction other than the laws of Israel.

     As counsel for the Company, we have examined such corporate records,  other
documents,  and such questions of Israeli law as we have considered necessary or
appropriate  for the  purposes  of this  opinion  and,  upon  the  basis of such
examination, advise you that in my opinion, the Shares, when paid for and issued
in  accordance  with the terms of the  Plan,  will be duly  authorized,  validly
issued, fully paid and non-assessable.

     We hereby  consent  to the  filing of this  opinion  as an  exhibit  to the
Registration Statement. This consent is not to be construed as an admission that
we are a party  whose  consent is  required  to be filed  with the  Registration
Statement under the provisions of the Securities Act.

                                            Very truly yours,

                                            /s/Dora Mer
                                            Dora Mer