The combination treatment with bromocriptine and clomiphene citrate was applied to 11 normoprolactinemic anovulatory patients who did not respond to clomiphene citrate alone. This combination treatment restored ovulation in 8 of these patients (72.7%). Conception was observed in 2 patients (18.1%) out of 11. The patients who responded to combination treatment showed a significant increase in the serum level of estradiol in the preovulatory phase, of progesterone in the mid-luteal phase, and a significant decrease of serum prolactin. They also showed significant increase in the frequency of luteinizing hormone (LH) pulsatility on day 12 of the cycle from 1.38 +/- 0.86 to 3.75 +/- 0.83 pulses/4h. The 3 patients who did not respond to combination treatment showed no increase in the serum level of estradiol or progesterone, but showed increase in the frequency of LH pulsatility in spite of continuous anovulation. These results indicate that the combination treatment with bromocriptine and clomiphene citrate is effective for treatment of patients with normoprolactinemic anovulation who do not respond to clomiphene alone, and suggest that the mechanism of the effect of combination treatment is related to an increase in the frequency of LH pulsatility caused by bromocriptine, which in turn stimulates follicular maturation.