This study evaluated the influence of bile acid load on the DNA distribution pattern of proliferated bile ductules and cholangiocarcinoma induced by diisopropanolnitrosamine. Ninety hamsters were separated into control, tauro- and deoxycholic acid (DCA) groups. The DNA distribution pattern of intrahepatic lesions at 15–25 weeks was measured by cytofluorometry and classified into three types: I (-A, -B), II and III, according to the degree of dispersion on the DNA histogram. Regarding proliferated bile ductule lesions, all groups showed an increase in cell populations, indicating the dispersion of nuclear DNA content from the 4C to 6C ranges over the course of 25 weeks, and two groups with bile acids, especially the DCA group, revealed significant high incidences of lesions with type I-B plus II compared with those in the control group (p < 0.05, 0.01). Changes in carcinoma types were similar to those of bile ductule lesions, and the tumors in the DCA group had a significant high frequency of type II plus III (p < 0.05). In addition, heterogeneity of the DNA distribution pattern was observed within individual lesions of not only carcinoma but also bile ductules. These results suggest that bile acid load, especially DCA, promotes an increase in nuclear DNA content or DNA polyploidization and enhances the distribution of the DNA pattern of proliferating bile ductules and carcinoma. Furthermore, a bile ductule-carcinoma sequence may be present in the development of cholangiocarcinoma.