This study examines the relationship between hyperbilirubinemia and appendicitis. It was hypothesized that an association exists between the presence of appendiceal perforation and hyperbilirubinemia. Patients with liver function tests on admission and pathologically confirmed appendicitis were included in the study. Age, duration of symptoms, temperature, white blood cell counts, systemic inflammatory response score, and bilirubin levels were independent variables in a logistic regression analysis assessing factors predicting the presence or absence of appendiceal gangrene/perforation. Elevated total bilirubin levels (>1 mg/dl) were found in 59 (38%) of 157 patients. Patients with gangrene/perforation were significantly (p = 0.004) more likely to have hyperbilirubinemia than those with acute suppurative appendicitis. No statistical differences were observed for any of the other variables. On logistic regression the only significant relationship between the presence or absence of appendiceal gangrene and perforation was the presence of hyperbilirubinemia (p = 0.031, 95% confidence interval 1.11-7.6). The odds of appendiceal perforation are three times higher (odds ratio 2.96) for patients with hyperbilirubinemia compared to those with normal bilirubin levels. Hyperbilirubinemia is frequently associated with appendicitis. Elevated bilirubin levels have a predictive potential for the diagnosis of appendiceal perforation.