Securities and Exchange Commission
December 7, 1999
Page 1

                                                                    Exhibit 5.1
                        Esanu Katsky Korins & Siger, LLP
                                605 Third Avenue
                            New York, New York 10158
                            Telephone: (212) 953-6000
                               Fax: (212) 953-6899

                                December 28, 1999


Securities and Exchange Commission                                    13146-002
450 Fifth Street, NW
Washington, D.C. 20549

               Re:    Netsmart Technologies, Inc.; File No. 333-91907

Ladies and Gentlemen:

        We refer to the registration  statement on Form S-3, File. No. 333-91907
(the  "Registration  Statement"),  under the  Securities Act of 1933, as amended
(the "Act"), filed by Netsmart  Technologies,  Inc., a Delaware corporation (the
"Company"),  with the Securities and Exchange  Commission.  Terms defined in the
Registration  Statement and not otherwise defined in this opinion shall have the
same meanings in this opinion as in the Registration Statement.

        We have examined the  originals or  photocopies  or certified  copies of
such records of the Company,  certificates of officers of the Company and public
officials,  and other  documents as we have deemed  relevant and  necessary as a
basis  for the  opinion  hereinafter  expressed.  In such  examination,  we have
assumed the  genuineness of all  signatures,  the  authenticity of all documents
submitted to us as certified  copies or photocopies and the  authenticity of the
originals of such latter documents.

        Based on our examination mentioned above, we are of the opinion that the
shares of common stock registered  pursuant to the  Registration  Statement have
been duly  authorized and when issued upon exercise of the warrants as described
in  the   Registration   Statement,   will  be  duly  issued,   fully  paid  and
non-assessable.

        Please note that Asher S. Levitsky, who is of counsel to this firm, and
the Asher S. Levitsky P.C. Defined Benefit Plan, of which Mr. Levitsky is the
trustee and beneficiary, are stockholders of the Company.

        We hereby  consent to the filing of this  opinion as Exhibit  5.1 to the
Registration Statement and to the reference to our firm under "Legal Matters" in
the related Prospectus.  In giving the foregoing consent, we do not hereby admit
that we are in the category of persons whose consent is required under Section 7
of the  Act  or the  rules  and  regulations  of  the  Securities  and  Exchange
Commission.

                                            Very truly yours,


                                            ESANU KATSKY KORINS & SIGER, LLP