**EXHIBIT      31.2**

| 1. | I                have reviewed this annual report on Form 10-K of PaineWebber R&D                Partners III, L.P. (the“Partnership”); |
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| 2. | Based                on my knowledge, this annual 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                annual report; |
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| 3. | Based                on my knowledge, the financial statements, and other financial information                included in this annual report, fairly present in all material respects                the financial condition, results of operations and cash flows of                the                Partnership as of, and for, the periods presented in this annual                report; |
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| 4. | The                Partnership’s other certifying officers and I are responsible for                establishing and maintaining disclosure controls and procedures (as                defined in Exchange Act Rules 13(a)-15(e) and 15(d)-15(e) for the                Partnership and we have: |
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|   |   | (a) | designed                such disclosure controls and procedures to ensure that material                information relating to the Partnership is made known to us by others                within the Partnership, particularly during the period in which this                annual report is being prepared; |
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|   |   | (b) | evaluated                the effectiveness of the Partnership’s disclosure controls and procedures                as of a date within 90 days prior to the filing date of this annual                report                (the “Evaluation Date”); and |
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|   |   | (c) | disclosed                in the annual report any change in the Partnership’s internal control over                financial reporting (as defined in Exchange Act Rules 13(a)-15(f)                and                15(d)-15(f)) that occurred during the Partnership’s fourth fiscal quarter                that has materially affected, or is reasonably likely to materially                affect                the Partnership’s internal control over financial                reporting; |
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| 5. | The                Partnership’s other certifying officers and I have disclosed, based on our                most recent evaluation, to the Partnership’s auditors and the audit                committee of the board of directors of the Partnership’s general partner                (or persons performing the equivalent                function): |
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|   |   | (a) | all                significant deficiencies in the design or operation of internal controls                which could adversely affect the Partnership’s ability to record, process,                summarize and report financial data and have identified for the                Partnership’s auditors any material weaknesses in internal controls;                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 Partnership’s internal                controls. |
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| Date: March              31, 2006 | By:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          | /s/ Robert              J.              Chersi |
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|                                   | Name:                  Robert J. ChersiTitle:                    Vice President                             (Principal Financial and Accounting Officer)                             of PaineWebber Development Corporation,              General                Partner of the Partnership |
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