Background: Complicated acute cholecystitis, for example when empyema or gangrene is present, is associated with increased postoperative morbidity and mortality rates. The aim of this study was to determine the correlation between sex, the severity of acute cholecystitis and the outcome of laparoscopic cholecystectomy. Methods: Of 674 patients in whom laparoscopic cholecystectomy was attempted, 348 had chronic cholecystitis and 326 had acute cholecystitis. The medical records of the latter were reviewed retrospectively. Results: The proportion of male patients significantly increased with the severity of cholecystitis: 37.4 per cent of those with chronic cholecystitis were men, compared with 44.4 per cent of those with uncomplicated acute cholecystitis and 57 per cent of those with complicated acute cholecystitis (P = 0.001). Multivariate analysis showed that advanced age (odds ratio 2.24; P = 0.004) and male sex (odds ratio 1.76; P = 0.029) independently predicted complicated acute cholecystitis. The conversion rate to open operation was 6.4 per cent in men and 5.9 per cent in women (P = 0.843). The postoperative complication rate was 10.3 and 8.2 per cent respectively (P = 0.528). Conclusion: Male sex was identified as a risk factor for more severe acute cholecystitis, but outcome for men after laparoscopic cholecystectomy was not significantly different from that for women.