Time course changes in bone mineral density and calcium metabolism after oophorectomy were investigated in comparison with those in hysterectomized and pre-operated women, retrospectively. A total of 191 women who had a regular menstrual period for 1 year prior to entering the study or to the operation, were divided into 3 groups; group 1 consisted of 33 women who were admitted to receive a gynecological operation (pre-OP group), group 2 consisted of 57 women who received hysterectomy within 5 years prior to entering the study (HX group) and group 3 consisted of 101 women who received hysto-oophorectomy (bilateral) at the same timing as the HX group (OOX group). All the subjects had their bone mineral density measured at the lumbar vertebrae (L2-4BMD) by means of dual energy X-ray absorptiometry (DXA) and at the metacarpal bone by the microdensitometrical (MD) method. Serum and urinary parameters related to bone and calcium metabolism were also evaluated. After dividing the subjects in accordance with the length of time after the operation, the time course changes in each parameter were calculated. In the 2 years after OOX, the L2-4BMD decreased significantly and rapidly, and the change in L2-4BMD in the subsequent period was quiescent. In the HX group, there was no significant change in L2-4BMD. When the period after the OOX was divided into 2 subcategories in accordance with the speed of decline in lumbar BMD as the rapid and the slow phases, the time course changes in blood and urine parameters showed different trends.(ABSTRACT TRUNCATED AT 250 WORDS)