Both hypothyroidism and hyperthyroidism in females have been well documented association with variable degrees of gonadal dysfunction. Hypothyroidism is associated mainly with oligomenorrhea whereas thyreotoxicosis usually leads to hypomenorrhea and polymenorrhea. It is of note that many patients with infertility problems display thyroid abnormalities. Especially an increased prevalence of autoimmune thyroid diseases has been found. This article reviews the clinical aspects of thyroid function in relation to female reproductive system.