PURPOSE: Acute cholecystitis is one of the most frequent abdominal inflammatory processes. If untreated or misdiagnosed it can result in severe complications such as gallbladder rupture, abscesses, or peritonitis. We retrospectively reviewed a series of 71 consecutive patients with surgical confirmation of acute cholecystitis and now compare the results of the diagnostic techniques we used preoperatively. MATERIAL AND METHODS: Over 16 months, 71 consecutive patients (42 women and 29 men; age range: 34-84 years, mean: 58) with acute abdominal pain were operated on for acute cholecystitis at Cardarelli Hospital, Naples. Abdominal plain film was performed in 65 of 71 cases, abdominal US in 69 and abdominal CT in 6. On abdominal plain films, we retrospectively searched the following signs: densities projected over the gallbladder, linear calcifications in gallbladder walls, gallbladder enlargement, focal gas collections within the gallbladder, and air-fluid levels in the gallbladder lumen. On US images we looked for: gallbladder wall thickening (> 3 mm), intraluminal content in the gallbladder, pericholecystic fluid, US Murphy's sign, and gallbladder distension. On CT images, we investigated: gallbladder distension, wall thickening, intraluminal content, pericholecystic fluid, and inflammatory changes in pericholecystic fat. Associated complications of cholecystitis were also searched on all images. RESULTS: On plain abdominal films we found densities projected over the gallbladder (16.9%) and linear calcifications in the gallbladder wall (4.6%). Abdominal US demonstrated gallbladder wall thickening (56.5%), one or more gallstone(s) (85.5%), pericholecystic fluid (14.5%), gallbladder distension (46.4%), and US Murphy's sign (39.1%). Abdominal CT showed gallbladder wall thickening (83.3%), gallbladder distension (66.6%), pericholecystic fluid (66.6%), gallstones (50%), inflammatory changes in pericholecystic fat (33.3%), and increased bile density (> 20 HU) (33.3%). CONCLUSIONS: US appears to be the most useful imaging technique in patients with suspected acute cholecystitis, for both screening and final diagnosis. CT plays a limited role in the early assessment of these patients, but can be a useful tool in diagnosing acute cholecystitis in patients with questionable physical findings or in investigating related complications.