Received February 23, 2012
Accepted April 14, 2012

Objective: To evaluate the effect of metformin associated to clomiphene citrate on ovulation, and pregnancy rates in clomiphene citrate-resistant women with polycystic ovary syndrome. Methods: Patients with PCOS who received 2 cycles of clomiphene citrate (100 mg/day from days 5 to 9) were initially included in the study. Patients who did not respond to clomiphene citrate were randomly allocated to receive either metformin 850 mg twice daily (group 1) or placebo twice daily (group 2) taken for two months in a row. After that associated to CC (100 mg/day from days 5 to 9) for the two following cycles. Results: Compared with the control group, the metformin group had significantly higher ovulation (p=0,04), however, there was no significant difference in the pregnancy rate between the two groups. When patients were separated according to BMI, we observed that obese patients (>28) had higher ovulation rates in the metformin group than placebo group. However this result was not observed for patients with BMI <28. Conclusion: Metformin associated to CC improves ovulation and pregnancy rates in clomiphene citrate-resistant women with polycystic ovary syndrome, specially in obese patients.