Summary
Single luteal phase serum progesterone values were determined in 34 infertile Nigerian women with regular menstrual cycles. Endometrial biopsies were obtained simultaneously and histologically dated. Subsequent analysis showed that a serum progesterone value of 4•89 nmol/l (1•63 ng/ml) or above was always associated with a secretory endometrium. Taking a progesterone value of 6 nmol/l (2 ng/ml) as presumptive evidence of ovulation, 82 per cent of the patients were judged to have ovulated by both parameters. Two patients (6 per cent) had anovulatory cycles by both the serum progesterone as well as the endometrial histology.