To evaluate the clinical significance of anomalous pancreaticobiliary ductal union(PBDU), we analysed 11 cases(0.19%) of anomalous PBDU among 5675 cases performed ERCP from Jan. 1973 to Aug. 1992. According to the classification of Kimura et al., 4 cases were type 1(P-C union) and 7 cases type 2(C-P union). The length of common channel ranged from 1.5 cm to 3.1 cm(mean 1.9 cm). The common associated disease were choledochal cyst(7 cases), carcinoma of the gallbladder(5 cases) and biliary stone(3 cases). Four cases of carcinoma of the gallbladder were type 1. The incidence of anomalous PBDU was significantly higher in cases with carcinoma of the gallbladder(5 cases among 49 cases) than in case without carcinoma of the gallbladder(6 cases among 5626 cases). And the incidence of gallbladder carcinoma(45%) among the 11 cases of anomalous PBDU was significantly higher than that(0.78%) among those who did not have anomalous PBDU. In conclusion, the common associated diseases with the anomalous PBDU were choledochal cyst, carcinoma of the gallbladder and stone, and the anomalous PBDU may be risk factor in the development of carcinoma of the gllbladder.