EXHIBIT 31.1

CERTIFICATION

| | I,
David Aviezer, certify that:
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|1. |  | I
have reviewed this quarterly report on Form 10-Q of Protalix BioTherapeutics, Inc.;
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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 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
registrants other certifying officer 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 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 management or             other employees
who have a significant role in the registrants             internal control over
financial reporting.
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|Date:
May 15, 2007                                                                         |  |  |  | 
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|                                                                                           |  |  |  | 
|/s/
David Aviezer
      David Aviezer, Ph.D. 
       President and Chief Executive Officer |  |  |  |