Improving the diagnosis of acute appendicitis in order to prevent unnecessary surgery is crucial. This study was intended to identify the role of serum inflammatory markers in patients with preliminary diagnosis of acute appendicitis with a retrospective design. Eighty-five patients with the preliminary diagnosis of acute appendicitis were recruited in this study within the period of November-December 2003. The avarage age was 31.8 years (ranged from 15 to 85). There were 62 males (72.9%) and 23 females (27.1%). In addition to performing routine tests, preoperative serum samples were obtained from the patients to measure C-reactive protein, interleukin-6, and interleukin-10. All the patients were operated on for a clinical suspicion of acute appendicitis. Depending on the macroscopic evidence during the operation and the histopathological examination of the specimen, the patients were separated into two groups: the ones who did not have acute appendicitis as the cause for acute abdomen (group I; n = 14) and the ones who had acute appendicitis (group II; n = 71). The ones who had acute appendicitis (group II) were further grouped as noncomplicated appendicitis (group IIA; n = 44) and complicated appendicitis (group IIB; n = 27). Being a male with elevated levels of leukocytes (white blood cells, WBC); C-reactive protein (CRP), interleukin-6 (IL-6); and interleukin-10 increased the probability of having acute appendicitis in patients with evidences of acute abdomen. The risk of complication of acute appendicitis significantly increased when patients had increased levels of C-reactive protein, increased erythrocyte sedimentation rate, and increased interleukin-6 levels, had symptoms for more than 24 h, and were female. Interleukin-10 levels within normal range might be helpful in eliminating the possibility of acute appendicitis. Thus, elevated levels of WBC, IL-6 and CRP might be helpful in confirming a potential diagnosis of acute appendicitis. In addition, normal levels of IL-10 might be of additional help to possibly rule out the diagnosis of acute appendicitis.