We obtained blood samples from 88 women 45–58 yr old who were having cyclic menses every 1–2 mth (37 women, 133 samples) or were amenorrheic for > 3 mth (51 women, 310 samples). Samples were obtained at intervals of 3–4 mth and analyzed for estrogens, androgens and gonadotropins using radioimmunoassay techniques. There was a gradual decline in the concentrations of estrone (E 1), estradiol (E 2), estrone sulfate (E 1SO 4) and progesterone (P) as the time from the last menses increased. A relatively stable concentration was reached in 12 mth for E 1, E 2, and E 1SO 4 and in 2 mth for P. The concentrations of testosterone, dihydrotestosterone, androstenedione, dehydroepiandrosterone and dehydroepiandrosterone sulfate remained relatively constant as the time from the last menses increased. There was no apparent difference in the mean values of any of these hormones for any time interval from the last menses. The concentrations of both luteinizing hormone (LH) and follicle stimulating (FSH) were noted to increase initially but they appeared to become stable after 12 mth for FSH and after only 6 mth for LH. Using only the measurements made on the initial blood samples obtained in all patients, we found significant correlations between FSH concentrations and the concentrations of E 1, E 2 and E 1SO 4 for women who were less than 3 mth from a menses as well as those whose last menses had occurred 3 or more mth previously. The correlations were generally not significant for LH in either groups of women. Although a number of the amenorrheic women had estrogen levels which were compatible with endometrial stimulation, these women experienced vaginal bleeding only rarely, and there was no predictive element that we could find to identify which women would have episodes of vaginal bleeding.