**Exhibit      12.1**

**CERTIFICATION      PURSUANT TO**

**SECTION      302(a) OF THE SARBANES-OXLEY ACT OF 2002 **

| 1. | I                  have reviewed this annual report on Form 20-F of RADVision                  Ltd.; |
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| 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; |
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| 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; |
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| 4. | The                registrant’s other certifying officer(s) 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: |
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|   | (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; |
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|   | (b)  | [Paragraph                    omitted pursuant to SEC Release Nos. 33-8238 and                    34-47986] |
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|   | (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 |
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|   | (d) | Disclosed                  in this report any change in the registrant’s internal control over                  financial reporting that occurred during the period covered by                  the annual                  report that has materially affected, or is reasonably likely to                  materially                  affect, the registrant’s internal control over financial reporting;                  and |
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| 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): |
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|   | (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 |
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|   | (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. |
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| Date: April 3, 2006                          |   |   |   |
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| /s/ Boaz              Raviv*                 |   |   |   |
| Boaz              Raviv                           |   |   |        |
| Chief              Executive              Officer |   |   |   |

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