I Persson (Department of Obstetrics and Gynecology, University Hospital, S-751 85 Uppsala, Sweden), Naessén T, Adami H O, Bergström R, Lagrelius A, Möllerstram G, Pettersson B and von Hamca K. Reduced hip fracture in women with endometrial cancer. International Journal of Epidemidogy 1992; 21: 636–642. The effect of excessive endogenous oestrogens on the risk of hip fracture was investigated in a populatiombssed cohort of 2111 women with endomatrial carcinoma who were followed up from age 50 years regarding the occurrence of a first hip fracture. Overall, 77 cases of hip fracture were observed, as against 120.8 expected, which nmant a significantly reduced relative risk, standardized incidence ratio (SIR) = 0.6, 95% confidence interval (CI): 0.5-0.8. This possible protecthe effect was significant for cervical fractum, SIR = 0.6 (95% CI: 0.4–0.81, but not for trochanteric, SIR = 0.8 (95% CI: 0.5–1 .I). Age at endometriel cancer diegnm's was not a determinant of the risk of hip fracture. A lowered relative risk was prasent regardless of age at diagnosis and persisted during the entire follow-up period and into advanced ages. A case-control anatysis within the cohort, and based on medical record data, indicated that a higher weight might be associated with a greeter protective effect, as compared with a lower weight. Expsure to exogenous oestrogens was infrequent and could not have explained the present result. We conclude that persistent influence of oestrogens, notably of endogenous origin, can reduce the risk of hip fractures, and that this protective effect may be long-lasting and extend to advanced ages.