AIM: Acute appendicitis is one of the most common pathology requiring emergency operations, and if perforated, can cause morbidity and mortality. The serum bilirubin levels were studied to see whether an elevation predicted perforation. MATERIAL AND METHODS: In a retrospective cohort study the medical files of 221 patients who were operated for acute appendicitis were reviewed. RESULTS:Total and indirect bilirubin levels were significantly higher in patients with a perforated appendicitis compared with patients with simple appendicitis. Elevated serum bilirubin had a sensitivity of 50.00 (95% CI 29.93 to 70.07) and a specificity of 80.73 (95% CI 74.43 to 86.05) when predicting a perforated appendicitis. CONCLUSIONS: Appendiceal perforation may be accompanied with elevated serum bilirubin level. Assessment of bilirubin levels must be a part of the initial evaluation of a suspected appendicitis in the emergency room.