Although reproductive factors have been shown to be related to the composition of bile and functioning of the biliary system, their relationship with biliary tract cancer has not been studied in detail. Between 1984 and 1987 we conducted a case-control study of 75 women with cancer of the biliary tract and 252 controls from the general population. An interviewer-administered questionnaire was used to collect information on reproductive history. The information was obtained from the responders themselves (direct response) or from relatives (indirect response). Our results indicate that younger age at menarche, early age at first pregnancy, higher number of pregnancies and prolonged fertility may enhance the risk of cancer of the biliary tract. Overall, increased exposure to endogenous oestrogens and progesterone constitutes a higher risk. © 1994 Wiley-Liss, Inc.