During a 30 months period, two women of primary hypothyroidism (2/13; 1.04%) presented with features of polycystic ovary syndrome (PCOS). In hypothyroidism, sex hormone binding globulin levels are decreased; increased conversion of androstenedione to testosterone, and aromatization to estradiol are present, all these being an exaggeration of biochemical changes characteristic of PCOS. Besides, metabolic clearance rates of androstenedione and estrone, the putative mediators of PCOS, are reduced. Hypothyroidism can either initiate, maintain or worsen the syndrome. Correction of hypothyroidism when present, would therefore form an important aspect in the management of infertility associated with PCOS.