Background Anovulation is one of the common causes of infertility. Polycystic ovary syndrome (PCOS) is the most common disorder with chronic Anovulation. To the best of our knowledge, insulin resistance relates significantly to PCOS. Therefore administration of insulin-sensitizing drugs such as pioglitazone can be used for ovulation stimulation in PCO patients. Methods After obtaining approval from the Ethics Committee of Mashhad University of Medical Sciences, 61 patients with PCOS were enrolled in the study based on inclusion/ exclusion criteria. Patients were divided into two groups. The first group received 30 mg (mg) of pioglitazone daily from the second day of the menstrual period. The second one received a placebo. 150 mg clomiphene citrate was administered from the third to the seventh day of the menstrual cycle. Vaginal sonography was performed in all women, and in cases with the mature follicle, intrauterine insemination was conducted after human chorionic gonadotropin injection. Ovary stimulation and pregnancy rate were compared between groups. Results There were no differences between groups regard to demographic characteristics and infertility type. Body mass index was higher in the pioglitazone group (28.3 ± 3.8 versus 26.2 ± 3.5, P value = 0.047). The size of the follicle was not significantly different between groups (2.2 ± 1.4 versus 1.3 ± 1.1, P value = 0.742). pregnancy rate [4 (12.9%) versus 4 (13.3%), P value = 1] had no differences between groups. Conclusion Although the number of follicles was higher in the pioglitazone group, our study showed no differences in ovary stimulation and pregnancy rate.