**Exhibit        31.1**

**CERTIFICATION        PURSUANT TO**

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

| 1. | I                  have reviewed this Quarterly Report on Form 10-Q of the Claymore                  MACROshares Oil Down Holding Trust; |
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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                  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. | 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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|   | c. | 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 |
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| 5. | The                  other certifying officer(s) and I have disclosed, based on our                  most recent                  evaluation of internal control over financial reporting, to the                  registrant's auditors, the board of managers of Macro Securities                  Depositor, LLC, the audit committee of Claymore Securities, Inc.,                  Claymore                  Securities, Inc.'s auditors and the audit committee of MacroMarkets                  LLC                  (or persons performing the equivalent                  functions): |
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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 persons who have                  a                  significant role in the registrant's internal control over financial                  reporting. |
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|   | /s/                    Samuel Masucci, IIISamuel                  Masucci, IIIOn                  behalf of the Registrant and                  as Chief Executive Officer |
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