BACKGROUND Acute cholecystitis is a common diagnosis for which surgery is usually indicated. However, the heterogeneity of clinical presentation makes it difficult to standardize management. The variation in clinical presentation is influenced by both patient-dependent and disease-specific factors. A preoperative clinical scoring system designed to included patient-dependent and clinical factors might be a useful tool in clinical decision making. METHODS The data of patients undergoing laparoscopic cholecystectomy for acute cholecystitis in a university hospital were retrospectively reviewed. Patient-dependent factors (age, sex, body mass index, and American Society of Anesthesiologists score) and disease-specific factors (history of biliary colics, white blood count, C-reactive protein, and gallbladder wall thickness) were used to compute a clinical score between zero and nine for each patient. Cholecystitis was classified as mild (score ≤ 3), moderate (4 ≤ score ≤ 6), or severe (score ≥ 7). RESULTS Cholecystitis was mild in 45 cases, moderate in 105 cases, and severe in 27 cases. Among patient-dependent factors, the male gender, age >65 y, and American Society of Anesthesiologists score >2 correlated significantly with high scores, P = 0.001. Equally, high white blood count, elevated C-reactive protein, and gallbladder wall thickness >4 mm correlated significantly with high scores, P = 0.001. These findings were confirmed on multivariate analyses. High scores correlated significantly with the duration of surgery (P = 0.007), the need of intensive care unit management (P = 0.001) and the length of stay (P = 0.001). However, there was no significant association between the preoperative score and the rate of conversion (P = 0.103) or the rate of complication (P = 0.209). CONCLUSIONS This preoperative clinical scoring system has a potential to select patients with severe cholecystitis and therefore might be a useful tool in clinical decision making.