Infertility is a medico social problem in Nigeria and it accounts for 40 percent of our outpatient gynaecological consultations; therefore the need to evaluate the two common presumptive methods of ovulation (serum progesterone and endometrial history) is indicated. An endometrial biopsy and three blood samples taken between M-4 and M-11 (4 and 11 days to the next menstruation) for progesterone determination in the luteal phase of the cycles of 50 infertile Nigerian women were analyzed. The methods were compared for confirmation of ovulation and evaluation of luteal functions. Total luteal phase progesterone value of 11.3 nmol/1 or greater was consistent with ovulation (secretory endometrium) in 90% of the cycles. 41 cycles yielded sufficient information to compare the two methods for evaluation of luteal function. The total progesterone value of 15 nmol/1 or greater was consistent with in-phase biopsies. Twenty eight (68.3%) of the cycles showed evidence of In-Phase (IP,) biopsies while thirteen (32.7%) showed out of phase (00P) biopsies suggestive of abnormal luteal function. The mean progesterone levels of patients with IP biopsies were significantly higher than those with 00P biopsies (P < 0.0001). Compared to studies by other workers using single midluteal progesterone assay, it seems multiple progesterone assay does not confer added advantage in confirming ovulation or in evaluation of luteal function. It is suggested that simultaneous measurements of serum progesterone levels with endometrial biopsies should be used to document ovulation and luteal function in infertile Nigerian women in view of the scarcity of ultrasonographic machines and emerging new technologies in our practice.