The pattern of thickening of the extrahepatic bile duct on computed tomography was analysed in 30 cases with recurrent pyogenic cholangitis diagnosed by surgery (n=19) or clinical basis (n=11). The mean wall thickness of the extrahepatic bile duct was 3.3mm (range, 1-6.3mm). Diffuse thickening of the extrahepatic bile ductal wall was demonstrated in 26 of 30 cases. Diffuse thickening of the extrahepatic bile duct in recurrent pyogenic cholangitis may be differentiated from focal thickening of duct in a common duct cancer or pancreatic cancer.