The effects on bone density of long-term depot medroxyprogesterone acetate (DMPA) use were investigated in a cross-sectional study of 185 clients 17-52 years of age at family planning clinics in Portsmouth and Manchester, England, who had been receiving contraceptive injections for 1-16 years (median, 5 years). Dual energy x-ray measurements of bone density of the femoral neck and lumbar spine, as well as venous blood samples, were taken prior to the women's next DMPA injection (1994-96). 153 women had serum estradiol levels under 150 pmol/l--the value considered adequate to maintain bone density. The mean bone density of the lumbar spine compared with the population mean for women 20-59 years old yielded a Z score of minus 0.332 (95% confidence interval, -0.510 to -0.154; p 0.001). There was a weak, nonsignificant correlation between lumbar spine Z score and years of DMPA use. Mean density of the femoral neck did not differ significantly from the normal population mean. There was no significant correlation between serum estradiol level and either bone density score. Overall, these findings provide no evidence that DMPA-induced amenorrhea places women at significant risk of further bone loss or that supplemental estrogen is required.