The bone and lipid metabolisms in Japanese oophorectomized (OVX) women and effects of estrogen replacement therapy (ERT) were investigated. Three hundred and two OVX women (mean age of 41.6) and 164 premenopausal women (mean age of 42.1) were examined. BMD of the lumbar spine, serum Ca, P, Al-p, total cholesterol (T-C), HDL-C and LDL-C were measured every three months. BMD within 2 years after OVX was not significantly decreased. The mean BMD between 2 and 5 years or over 10 years after OVX was 0.83 (p < 0.01) and 0.69 (p < 0.001), respectively. Serum Ca and P were increased for 2 years and Al-p was increased for 10 years after OVX. To investigate the effect of ERT on BMD, OVX women were divided into 3 groups: ERT, VD3 and no treatment groups. After 12 months of treatment, the mean % BMD in each group was 102.9, 100.6 and 97.8, respectively. T-C or LDL-C was gradually increased in 10 years after OVX. After 15 months of ERT, the mean percentages HDL-C and LDL-C in hyperlipidemic women (LDL-C > or = 150) were 110.5 (p < 0.05) and 75.2 (p < 0.001). ERT may be requisite for OVX women and effective in preventing increased bone turnover and hyperlipidemism following OVX.