Exhibit 31.1
 CERTIFICATION
OF CHIEF EXECUTIVE OFFICER
 
 I, John
B. Rush, certify that:
 
 1.           I
have reviewed this Amendment No. 1 to the annual report on Form 10-K of
North American Scientific, Inc.;
 
 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 registrant as of, and
for, the periods presented in this report;
 
 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)) and internal control over financial
reporting (as defined in Exchange Act Rules 13a-15(f) and 15-d-15(f)) for the
registrant and have:
 
 a)
              Designed
      such disclosure controls and procedures, or caused such disclosure control
      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;
 
 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 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
 
 d)      Disclosed
in this report any changes 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
 
 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 registrant'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 registrant'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 rolein the registrant's internal control
      over financial reporting.
 
 Date:
February 27, 2009
  /s/JOHN
      B. RUSHJohn
      B. Rush
                  President
      and Chief Executive Officer