Acalculous cholecystitis is an inflammation of the gallbladder in the absence of gallstones. Diagnosing this condition is often difficult because of the patient's debilitated medical condition and because of the limitation of biliary imaging technique. Nonetheless, its recognition and therapy are critically important, for if left untreated, many patients will die. During 10 years and 6 months from January 1986 to June 1996, 52 patients underwent assessment and treatment for acalculous cholecystitis at the Department of Surgery, Kyungpook National University Hospital. A clinical analysis of those patients was done and the following results were obtained: The incidence rate was 3.5%. The most prevalent age group was the seventh decade (13cases), and the male-to-female ratio was 1.4 : 1. Possible etiologic factors were found in 25 cases (48.1%). These factors were surgery in 5 cases (9.6%), trauma in 5 cases (9.6%), sepsis in 5 cases (9.6%), clonorchiasis in 5 cases (9.6%), and others in 5 cases(9.6%). Neither Ascariasis nor Salmonellosis was found as a predisposing factor in this study.The main cardinal symptoms and physical signs were similar to those of calculous cholecystitis. The sensitivities of diagnostic imaging by ultrasonography and computed tomography were 88.4% and 100%, respectively. Of the 52 patients, 46 cases underwent cholecystectomy, and 6 cases were initially treated by percutaneous transhepatic cholecystostomy. Of these 6 cases, two patients had cholecystostomies during subsequent abdominal operations for other conditions. Two patients had the cholecystostomy tube removed 2 months after an uneventful recovery and have had no further biliary problems. The other two patients died. The operative findings were cholecystitis only in 26 cases (56.5%), cholecystitis with localized peritonitis in 18 cases (39.1%), and cholecystitis with generalized peritonitis in 2 cases (4.3%). Postoperative complications occurred in 16 cases (34.8%), and wound infection was the most common complication (62.5% of all complications).The overall mortality was 9.6%. Conclusively, acalculous cholecystitis had high morbidity and mortality in this study. Once the diagnosis of acalculous cholecystitis is made, the gallbladder should be drained or removed. A decision as to the best approach depends on the specific situation and will require close cooperation between the internist, the surgeon, and the radiologist.