OBJECTIVE The purpose of this study was to evaluate the effectiveness and endocrine response of oral contraceptive ovarian suppression followed by clomiphene citrate in patients who previously were clomiphene citrate resistant. METHODS Forty-eight patients from a private tertiary infertility clinic were assigned randomly prospectively to either group 1 (oral contraceptive/clomiphene citrate), which received continuous oral contraceptives followed by clomiphene citrate, or to group 2 (control) received no treatment in the cycle before clomiphene citrate treatment. On day 3, 17 beta-estradiol, follicle-stimulating hormone, luteinizing hormone, and androgens were assayed before and after treatment. Follicle growth, ovulation, and pregnancy were evaluated. The Student t test and analysis of variance were used for statistical significance. RESULTS The oral contraceptive/clomiphene citrate group had a significantly higher percentage of patients who ovulated and of ovulatory cycles and pregnancies. Significantly lower levels of 17 beta-estradiol, luteinizing hormone, and androgen levels were seen in the oral contraceptive/clomiphene citrate group, with no significant changes in group 2. CONCLUSIONS Suppression of the ovary with oral contraceptives results in excellent rates of ovulation and pregnancy in patients who previously were resistant to clomiphene citrate. The decreases in ovarian androgens, luteinizing hormone, and 17 beta-estradiol may be responsible for the improved response.