Background:Acute appendicitis is the most common cause of acute abdomen in surgical emergency and subsequent surgery. The diagnosis is essentially based on the clinical grounds and as a result misdiagnosis and delay in surgical intervention is a common and crucial problem. Diagnostic delay often result in appendicular perforation and peritonitis with increased complications. Serum bilirubin and serum Procalcitonin have been shown to increase in perforated appendicitis and therefore can be used as markers. Aim:The purpose of this study is to evaluate the role of hyperbilirubinemia and raised serum Procalcitonin as predictors for appendiceal perforation or complicated appendicitis. Materials and methods: This study consisted of patients admitted with the clinical suspicion of acute appendicitis. A total of 50 patients who had histologically proven appendicitis were included in the study. Subsequent to hospital admission all patients underwent thorough physical examination and routine laboratory investigations. The patients were grouped as simple acute appendicitis or complicated appendicitis (appendicular perforation and/or gangrenous appendicitis). Results:Serum bilirubin and serum Procalcitonin were raised in a significant number of patients with complicated appendicitis. 17 of 20 patients with perforated appendicitis had bilirubin >1.5mg/dl (P<0.005). Sensitivity of serum bilirubin in predicting perforation was 85%, while specificity was 90%. 19 of 20 patients with perforated appendicitis had raised serum Procalcitonin levels (P<0.005). Sensitivity and specificity of serum Procalcitonin in predicting perforation was 95% and 83.33% respectively. Conclusion: Bilirubin and Procalcitonin are important preoperative biochemical markers and are effective in predicting perforation in patients with acute appendicitis.