We examined the relationship of reproductive history to cholecystectomy in a population-based sample of 1093 women aged 50 years and older. Number of pregnancies ranged from 0 to 13. Age and obesity were each significantly and independently associated with an increased risk of cholecystectomy. When adjusted for differences in age and obesity, those who had had five or more pregnancies had a significantly increased risk of cholecystectomy. We conclude that an increased risk of gallbladder disease may follow either obesity or multiple pregnancies. One possibly unifying hypothesis for the obesity and pregnancy association is sustained hyperestrogenemia.