To audit the appendectomies at our institute, and summarise atypical pathological results with a discussion of appropriate management. DESIGN. Retrospective study. Regional hospital, Hong Kong. All patients who underwent appendectomy for presumed acute appendicitis from June 2003 to June 2008 were recruited. Incidental appendectomy was excluded. Patient demographics, pathological findings, and surgical outcomes were analysed. RESULTS. The overall negative appendectomy rate was 18.2%. Female patients of reproductive age (11-50 years) conferred an independent risk for a higher negative appendectomy rate than other females (28.7% vs 11.5%; P<0.001). The overall perforation rate was 22.5%; the extremes of age (<11 or >70 years) conferred an independent risk of perforated appendicitis (25.2% vs 16.3%; P=0.002). Preoperative imaging was not associated with a lower negative appendectomy rate or rate for perforated appendicitis (P=0.205 and 0.218, respectively). Multivariate analysis suggested that a preoperative white cell count of less than 13.5 x 10(9) /L was an independent predictor of negative appendectomy (P<0.001); the body temperature and pulse rate of the patients with perforated appendicitis were higher than in those without perforation (P=0.004 and 0.003, respectively). Only 4.0% of the appendectomy specimens contained other appendiceal pathologies. Appendiceal diverticulitis was the most common inflammatory pathology, contributing to 2.7% of all appendectomies, followed by granulomatous appendicitis. In this series there were eight carcinoid tumours, three adenocarcinomas, two mucinous cystadenomas; tubular adenoma, metastatic deposition, mucinous cystadenocarcinoma and pseudomyxoma peritonei each occurred in one patient only. A more focused utilisation of preoperative imaging in females of reproductive age and patients at the extremes of age is suggested. Long-term follow-up should be offered to patients with granulomatous appendicitis and neoplastic appendiceal diseases.