Background: Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age. Polycystic ovary syndrome signs and symptoms often begin soon after menarche. In some cases, PCOS develops later during the reproductive years, for instance, in response to substantial weight gain. The PCOS produces symptoms in about 5-10% of women of reproductive age(12-45 years) and it is one of the leading causes of female subfertility.Women with PCOS suffer not only from subfertility, but also from a high rate of early pregnancy loss. About 30-50% of clinically confirmed early pregnancy loss are associated with PCOS.In addition to early pregnancy loss, women with PCOS have increased risk of recurrent miscarriage ,which defined as 3 or more consecutive pregnancy loss before 20 week. Metformin hydrochloride, an insulin sensitizing agent, has been shown to have encouraging effects on several aspect of PCOS like insulin sensitivity, plasma glucose concentration & lipid profile.It is found that using Metformin during pregnancy in women with PCOS may reduce the pregnancy loss and also reduce the risk of gestational diabetes,intrauterine growth retardation(IUGR) & preterm labor. Aim of study: To evaluate the role of Metformin in women with recurrent miscarriage & its effect on other pregnancy complications in women with PCOS. Patients, Materials & Methods: A prospective study done at gynecology outpatient clinic of AL-Batool Teaching Hospital in Baquba-Diyala -Iraq, from September 2012 to September 2016. A total of 100 cases were studied, all have aconfirmed diagnosis of PCOS depending on the following criteria:1)Oligo or amenorrhea (8 or fewer cycles per a year) , 2) signs of hyperandrogenism 3)ultrasound features of PCOS.All should have history of 3 or more recurrent first trimester miscarriage & they were invistigated for other causes of recurrent miscarriage. All cases were followed before getting pregnant and received Metformin for enhancing fertility & when they become pregnant, they were divided into two groups: the 1st group stopped using Metformin once they get pregnant while the 2nd group continued to use Metformin in a dose of 500-1000mg per day throughout pregnancy .Both groups are followed to determine pregnancy outcome. Results: Patients who continued to receive Metformin during pregnancy had better pregnancy outcome regarding early pregnancy loss and recurrent miscarriage, gestational diabetes development, IUGR & preterm labor. Conclusions: Metformin use during pregnancy improve pregnancy outcome in patients with polycystic ovary syndrome.