Postpartum thyroiditis is the most common endocrinologic disease. Although the incidence varies geographically, the entity develops in approximately 5% to 10% of all women. Postpartum thyroiditis is accompanied by a constellation of signs and symptoms, which can range from the extremely subtle to the overt, and has been linked to postpartum depression. Long-term follow-up of women in whom postpartum thyroiditis develops reveals a high rate of recurrence and a markedly increased risk for long-term hypothyroidism.