OBJECTIVE: The purpose of our study was to describe the CT findings of acute cholecystitis and apply previously proposed CT criteria for its diagnosis. MATERIALS AND METHODS: We retrospectively reviewed CT scans of 29 patients with proven acute cholecystitis. Scans were reviewed for gallstones, gallbladder distension, bile density, wall thickening, pericholecystic fluid, subserosal edema, pericholecystic stranding, and sloughed membranes. Previously published criteria were applied to determine the percentage of patients that met positive criteria for acute cholecystitis. RESULTS: The most common CT findings, in decreasing order of frequency, were wall thickening (n = 17), pericholecystic stranding (n = 15), distension (n = 12), pericholecystic fluid (n = 9), subserosal edema (n = 9), high-attenuation bile (n = 7), and sloughed membranes (n = 1). Of the 29 cases of acute cholecystitis, 15 met previously published CT criteria. CONCLUSION: CT can be useful in diagnosing acute cholecystitis. Common CT findings of acute cholecystitis include wall thickening, pericholecystic stranding, distention, high-attenuation bile, pericholecystic fluid, and subserosal edema. When these findings are present, the diagnosis of acute cholecystitis can be suggested. However, previously published CT criteria failed to identify a significant number of patients with acute cholecystitis.