Background:Preliminary studies suggest a multidimensional relationship of mood pathology with endocrine disturbances. Studies have found an increased risk of mood disorders in polycystic ovary syndrome (PCOS), and conversely, many of the medications commonly used in the treatment of bipolar affective disorder (BPAD) can have deleterious effects on blood levels of reproductive hormones and consequently on the hypothalamic–pituitary–gonadal (HPG) axis and reproductive function. Furthermore, there is evidence of reproductive dysfunction in women with BPAD before treatment.Objectives:To assess the comorbidity of PCOS in patients of BPAD and to study risk factors associated with this comorbidity.Materials and Methods:Two hundred female patients with the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition diagnosis of BPAD, between ages of 15 and 45 years, were evaluated by an endocrinologist. Patients reporting menstrual disturbances or having any stigmata of PCOS were further subjected to hormonal analysis, which included luteinizing hormone, follicle-stimulating hormone, prolactin, and testosterone, in the early follicular phase of menstrual cycle. Diagnosis of PCOS was made as per the NIH criteria.Results:Of 200 patients, 46 (23%) were diagnosed as having PCOS. Forty-five percent (n = 90) reported menstrual disturbances while 27% (n = 54) had polycystic ovaries on ultrasonography. 19.2% of the patients diagnosed as PCOS had a history of valproate intake while 27.90% patients had no such history (P = 0.15). No significant difference (P = 0.07) was found in the prevalence of PCOS among various drug groups (including group on multiple mood stabilizers).Conclusion:A higher prevalence of PCOS is seen in BPAD, irrespective of pharmacotherapy, suggesting a common link between the disorders which might be in the form of disturbance in HPG axis.