PURPOSE: We compared CT findings of thickened wall-type gallbladder cancer with those of complicated cholecystitis. MATERIALS AND METHODS: We retrospectively reviewed abdominal CT scans of ten patients with thickened wall-type gallbladder cancer and eight patients with complicated cholecystitis, from March 1991 to November 1995. RESULTS: CT findings of thickened wall-type gallbladder cancer showed diffuse or focal wallthickening. Wall thickness was 5.3-18.0 mm(mean value, 12.2mm ; n=10). Gallbladder wall thickness of complicatedcholecystitis was 3.0-14.0mm (mean value, 6.6mm ; n=8). Statistical significance was noted between thickened wall-type gallbladder cancer and complicated cholecytitis(p<0.0029). Irregular wall thickening was noted in 7/10cases of thickened wall-type gallbladder cancer(70%). Regular wall thickening was noted in 6/8 cases of complicated cholecystitis(75%). The luminal diameter of thickened wall-type gallbladder cancer was 3.3-5.4cm (meanvalue, 4.2cm ; n=10). The luminal diameter of complicated cholecystitis was 5.2-8.0cm (mean value, 6.5cm ; n=8).Statistical significance was noted between thickened wall-type gallbladder cancer and complicated cholecystitis(p<0.0003). The halo sign was noted in only 3/8 cases of complicated cholecystitis(38%). Secondary findings of thickened wall-type gallbladder caner was lymphadenopathy in 3/10 cases(30%), and liver invasion in 2/10 cases(20%). Secondary findings of complicated cholecystitis were liver abscess in 2/8 cases(25%), and RLQ abdominal fluid collection and pleural effusion in 4/8 cases(50%). CONCLUSION: Differential factors of thickened wall-type gallbladder cancer from complicated cholecystits are gallbladder wall thickness, regularity of wall thickness, halo sign, secondary findings and luminal distention.