Exhibit 31.1

                            CERTIFICATION PURSUANT TO
                SECTION 302(a) OF THE SARBANES-OXLEY ACT OF 2002

I, Gad Tamari, certify that:

1. I have reviewed this quarterly report on Form 10-Q of RADVision Ltd.;

2. Based on my knowledge, this report does not contain any untrue statement of a
material fact or omit to state a material fact  necessary to make the statements
made, in light of the  circumstances  under which such statements were made, not
misleading with respect to the period covered by this report;

3.  Based  on my  knowledge,  the  financial  statements,  and  other  financial
information included in this report, fairly present in all material respects the
financial  condition,  results of operations and cash flows of the registrant as
of, and for, the periods presented in this report;

4.  The  registrant's  other  certifying  officers  and  I are  responsible  for
establishing and maintaining  disclosure  controls and procedures (as defined in
Exchange Act Rules 13a-15(e) and 15d- 15(e)) for the registrant and have:

(a) Designed such disclosure controls and procedures,  or caused such disclosure
controls and  procedures to be designed  under our  supervision,  to ensure that
material  information  relating to the  registrant,  including its  consolidated
subsidiaries, is made known to us by others within those entities,  particularly
during the period in which this report is being prepared;

(b) [Paragraph omitted pursuant to SEC Release Nos. 33-8238 and 34-47986]

(c) Evaluated the  effectiveness  of the  registrant's  disclosure  controls and
procedures and presented in this report our conclusions  about the effectiveness
of the disclosure  controls and procedures,  as of the end of the period covered
by this report based on such evaluation; and

(d)  Disclosed in this report any change in the  registrant's  internal  control
over  financial  reporting  that occurred  during the  registrant's  most recent
fiscal quarter (the registrant's  fourth fiscal quarter in the case of an annual
report) that has  materially  affected,  or is  reasonably  likely to materially
affect, the registrant's internal control over financial reporting; and

5. The registrant's other certifying officers and I have disclosed, based on our
most recent  evaluation of internal  control over  financial  reporting,  to the
registrant's  auditors  and the audit  committee  of the  registrant's  board of
directors (or persons performing the equivalent function):

(a) All  significant  deficiencies  and  material  weaknesses  in the  design or
operation of internal  control over  financial  reporting  which are  reasonably
likely  to  adversely  affect  the  registrant's  ability  to  record,  process,
summarize and report financial information; and

(b) Any fraud,  whether  or not  material,  that  involves  management  or other
employees who have a significant role in the registrant's  internal control over
financial reporting.

Date: August 9, 2004

/s/Gad Tamari*
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Gad Tamari
Chief Executive Officer

     * The originally  executed copy of this Certification will be maintained at
the Company's offices and will be made available for inspection upon request.