Sheehan's syndrome occurs as a result of ischemic pituitary necrosis due to severe postpartum hemorrhage. The aim of the present study was to determine the clinical characteristics of Sheehan's syndrome in 20 patients (mean age 60.15 +/- 3.41 years) with typical obstetric history. The mean duration between time of diagnosis and date of the last delivery was 26.82 +/- 2.52 years (range 2-40 years). All patients had a history of massive hemorrhage at delivery and physical signs of Sheehan's syndrome. Fourteen patients (70.0%) lacked postpartum milk production and did not menstruate following delivery. Baseline and stimulated anterior pituitary hormone levels were measured in all patients. According to the hormonal values, 18 (90.0%) patients had secondary hypothyroidism, 11 (55.0%) had adrenal failure and all of them had hypogonadism, prolactin and growth hormone deficiency. Hyponatremia was present in seven patients (35.0%). Total or partially empty sella was revealed in all patients by magnetic resonance imaging. Diabetes insipidus was not found in any patient. We found that lack of lactation in the postpartum period and early menopause seemed the most important clues for diagnosis of Sheehan's syndrome, and inadequate prolactin and gonadotropin responses to stimulation tests were the most sensitive diagnostic signs in patients with severe postpartum hemorrhage.