Assessment to temporal relationship between levels of prolactin, LH, FSH, estradiol and progesterone in 12 ovulatory cycle was made. The serum prolactin concentrations were measured in daily blood samples by a double antibody radioimmunoassay methods. Thero was a tendency of increase in serum prolactin level during the late follicular phase, however no significant difference was found between the follicular and luteal phase(15.73±0.88ng/ml vs 12.93±0.37ng/ml). No correlation was found between levels of prolactin and, those of LH, FSH, estradiol and progesterone. The mean serum prolactin level during the normal ovulatory cycle was 14.3±0.47ng/ml(S.E). The data showed that the highest mean prolactin concentration was found on the day of +8 and +14 with second peak of estradiol and variation of episodic fluctuation or erratic spikes in the normal ovulatory menstrual cycle. These findings seems suggested of an inapparent physiologic role of prolaction in the regulation of ovulatory menstrual cycle.