The aim of this study is to determine the usefulness of different patterns of gallbladder mucosal enhancement on contrast-enhanced computed tomography (CT) for differentiating between gangrenous and uncomplicated acute cholecystitis. This retrospective evaluation involved 56 patients with histopathologically proved acute cholecystitis (32 with gangrenous and 24 with uncomplicated acute cholecystitis) who had preoperative contrast-enhanced CT imaging. CT in 38 patients showed a gallbladder mucosal enhancement pattern that could be categorized into continuous, discontinuous, and/or irregular categories. In the other 18 patients, the mucosal enhancement pattern could not be classified due to lack of mucosal enhancement or inadequate mucosal enhancement. On contrast-enhanced CT evaluation, continuous and discontinuous and/or irregular mucosal enhancement patterns were seen in 20 and 18 patients, respectively. Among the 20 patients with continuous mucosal enhancement, 17 had uncomplicated acute cholecystitis. Seventeen of the 18 patients with discontinuous and/or irregular mucosal enhancement had gangrenous cholecystitis. The sensitivity and positive predictive value (PPV) of discontinuous and/or irregular mucosal enhancement in the diagnosis of gangrenous cholecystitis were 30.3% and 94.4% (17 of 18), respectively. The sensitivity and PPV of continuous mucosal enhancement in the diagnosis of uncomplicated acute cholecystitis were 30.3% and 85.5% (17 of 20), respectively. There was a statistically significant difference (p = 0.0005) between the PPV of discontinuous and/or irregular (94.4%) and that of continuous (15%) mucosal enhancement for predicting gangrenous cholecystitis. The pattern of gallbladder mucosal enhancement on CT can be used as a reliable criterion for distinguishing acute, uncomplicated cholecystitis from gangrenous cholecystitis.