This study estimated the risk of hip fracture among postmenopausal females with and without estrogen drug exposure. The Kaiser-Permanente Medical Care Program in Portland, Oregon served as the setting and medical records the source of data. A retrospective case-control method that matched each female member hospitalized with a hip fracture (N = 168) between 1965-1975 with two control female members hospitalized for reasons other than a hip fracture was used. The estrogen exposure rate of cases was 29.2 per cent and of controls 36.0 per cent. The risk of hip fracture was reduced with postmenopausal and prefracture estrogen exposure (RML = 0.72, 95 per cent CL: 0.48-1.09). However, the number of cases was sufficient only to detect a reduction in risk of about 50 per cent or greater. A possible protective effect from estrogens was also suggested with oral estrogen exposure and with longer lengths of estrogen exposure.