To assess fracture risk following bilateral oophorectomy, we conducted a population-based retrospective cohort study among the 463 Rochester, Minnesota women who underwent bilateral oophorectomy for benign ovarian conditions in 1950-1979. During 7220 person-years of observation, there appeared to be a modest increase in the risk of distal forearm fractures (standardized morbidity ratio [SMR] 1.4; 95% CI 1.0-2.0) and vertebral fractures (SMR 1.9; 95% CI 1.3-2.8) but not hip fractures (SMR] 1.1; 95% CI 0.6-1.9). Although our statistical power was quite limited, there was a suggestion that women who became estrogen deficient at a young age were at greater risk of fracture. However, the youngest women were more likely to be on estrogen replacement therapy, and for longer durations, so that the average age at the onset of estrogen deficiency in this population was 47 years.