This case-control epidemiologic study examines the relationship between hormone replacement therapy (HRT) and risk for fractures of four sites among women 45 years of age and older. From October 1996 to May 2001, incident patients with distal forearm ( n=744), foot ( n=618), proximal humerus ( n=331), and pelvis ( n=109) fractures were recruited from five Kaiser Permanente Medical Centers in northern California. Controls ( n=1617) were selected at random from the same five medical centers over the same time period within strata defined by 5-year age group, gender, and white versus nonwhite or unknown recorded race/ethnicity. Trained interviewers collected information using a standardized questionnaire. Compared with postmenopausal women who never used HRT, postmenopausal women currently using HRT for at least 3 months had a decreased risk of fracture at the distal forearm (adjusted OR=0.55, 95% CI: 0.43, 0.72), proximal humerus (adjusted OR=0.51, 95% CI: 0.36, 0.74), and pelvis (adjusted OR=0.51, 95% CI: 0.27, 0.95), but not the foot (adjusted OR=1.05, 95% CI: 0.81, 1.35). Past use of HRT for more than 7 years also appeared to be associated with a reduced risk of fracture at the distal forearm and proximal humerus. The longer a woman went without HRT after her last menstrual period, the greater her risk of fracture in the distal forearm, proximal humerus, and pelvis. The findings of this study support long-term, current use of HRT for the prevention of osteoporotic fractures, but other risks and benefits also need to be considered.