Postpartum thyroiditis (PPT) is an autoimmune disorder that occurs in the first year after parturition. PPT is conceptualized as an exacerbation of an underlying autoimmune thyroiditis aggravated post partum. Prevalence of PPT is variable ranging from 1.1% to 16.7% in different regions of the world. PPT is characterized by periods of hyperthyroidism and/or hypothyroidism. Most, but not all patients, are euthyroid one year post partum. Treatment with beta-blockers is recommended only in some cases of hyperthyroidism and in hypothyroidism thyroid hormones should be given. The disease is recognized as an important health problem because its relationship with the probability of spontaneous fetal loss, the permanent impairment in neuropsychological development of the child, postpartum depression and subsequent permanent hypothyroidism predisposing to cardiovascular disease. It is suggested that screening for PPT should be conducted by measuring antiperoxidase antibodies.