Exhibit 12.1  CERTIFICATION  I,
Bernard Charlès, certify that:  1.I have
reviewed this annual report of Dassault Systèmes S.A. (the Company)
on Form 20-F for the period ending December 31, 2007, as filed
with the Securities and Exchange Commission on the date hereof (the Report);  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 Company as of, and for,
the periods presented in this Report;  4.The
Companys other certifying officer 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)) and internal control over
financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f))
for the Company 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 Company, 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)Designed
such internal control over financial reporting, or caused such internal control
over financial reporting to be designed under our supervision, to provide
reasonable assurance regarding the reliability of financial reporting and the
preparation of financial statements for external purposes in accordance with
generally accepted accounting principles;  c)Evaluated
the effectiveness of the Company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 Companys internal control over financial
reporting that occurred during the period covered by this Report that has
materially affected, or is reasonably likely to materially affect, the Companys
internal control over financial reporting; and  5.The
Companys other certifying officer and I have disclosed, based on our most
recent evaluation of internal control over financial reporting, to the Companys
auditors and the audit committee of the Companys board of directors
(or persons performing the equivalent functions):  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 Company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 Companys internal control over financial
reporting.  Date: April 4, 2008  /s/ BERNARD CHARLESName:
  Bernard CharlèsTitle:
  President and Chief Executive Officer