Introduction & Objective: Acute appendicitis is the most common cause for acute surgical abdominal pain, as soon as the diagnosis is documented, so appendectomy is necessary. Therefore it is important to demonstrate the specific and sensitive laboratory test for rapidly diagnosis or exclusion of disease. The purpose of this study is was evaluation of specificity and sensitivity of quantitative CRP and WBC and comparing them in diagnosis of acute appendicitis.

Materials & Methods: The method of this study was cross sectional descriptive over 185 patients who underwent operation with primary clinical diagnosis of acute appendicitis. Pathology study revealed appendicitis in 50 cases and 135 did not have pathologic abdominal problem.

Results: We showed that the specificity and sensitivity of CRP were 94.4% and 88.1% respectively and for WBC these were 98.1% and 37.1% respectively.

Conclusion: Negative CRP in the patients who admitted with abdominal pain with suspicious to acute appendicitis highly probable could rule out impression.