Cyclical etidronate is well established in the treatment of postmenopausal osteoporosis, but there are less data on its effects on bone loss in the early menopause. The aim of this study was to investigate the effects of cyclical etidronate therapy on bone loss in the lumbar spine and proximal femur in early menopausal women. Seventy-seven women aged over 40 yr who had ceased menstruating 6-36 mo prior to enrollment into the study were recruited into an open, randomized controlled study of cyclical etidronate therapy. Bone mineral density in the lumbar spine and proximal femur was assessed by dual-energy X-ray absorptiometry using a Lunar DPX bone densitometer. Fifty-five women completed the study. At the end of the 104-wk study period, significant treatment effects were observed in both the lumbar spine and the proximal femur. The estimated mean treatment effect in the lumbar spine was 2.79% (95% confidence interval 0.47, 5.10; p = 0.019). Corresponding figures for the femoral neck and greater trochanter were 3.23% (0.63, 5.82; p = 0. 016) and 3.77% (1.09, 6.45; p = 0.007). No significant differences between the groups were demonstrated at Ward's triangle. These results demonstrate that cyclical etidronate therapy prevents bone loss in the spine and proximal femur in early postmenopausal women and provides a safe and effective alternative for women who are unwilling or unable to tolerate hormone replacement therapy.