It is well known that the patients with anomalous arrangement of pancreatobiliary duct (AAPBD) are combined with biliary tract cancer. To clarify possible carcinogenesis of the gallbladder with AAPBD, DNA analysis of the gallbladder epithelium was performed in control (9 cases), AAPBD (26), gallbladder cancer confined in mucosa (10) and noncancerous epithelium around the gallbladder cancer (21). The mean values of DNA score, as already reported by us as an indicator of cell kinetics, were 12.1 (control), 27.2 (AAPBD, Type a), 13.3 (AAPBD, Type b), 14.8 (noncancerous epithelium around cancer) and 77.2 (gallbladder cancer confined in mucosa). The values of DNA score in the epithelium of AAPBD (Type a) showed significantly high level, which was next to that of cancer. Type a AAPBD may be supposed to have potential malignancy because of its accelerated cell cycle. But as Type b AAPBD without accelerated cell cycle combines cancer at least as often as Type a, further studies should be performed to reveal the relationship between cell cycle and malignancy.