BACKGROUND AND OBJECTIVE: Postoperative hypoparathyroidism is a rare, but complex endocrine disorder. The purpose of this case series study was to evaluate the symptoms, signs and sequelae of the disease in a major homogeneous patient group after the Chernobyl accident in the Ukraine. PATIENTS AND METHODS: This study is based on a random sample of 25 patients with symptomatic permanent hypoparathyroidism after surgical procedures on the thyroid for carcinoma following the Chernobyl accident in May 1986. They underwent physical examination and their parathyroid hormone and calcium levels in serum were determined. The signs, symptoms and sequelae of their disease were systematically assessed by a validated specific questionnaire. The extent of individual distress by the symptoms and signs were analysed by using a Likert scale (points between 1 = no and 5 = maximal distress). RESULTS: In 14 patients (56%) (age at time of operation: 18.24 +/- 4.26 years) paresthesias occurred at least every third day. Very frequent general symptoms were joint pains and hair loss (in 17 patients / 68%). 19 patients (76%) had enamel defects, 17 (68%) increasingly dry skin since the operation. Psychical symptoms like excitability (20 patients / 80%) and depressed mood since the operation (16 patients / 64%) were strikingly frequent. The patients were affected more by dry skin (2,76 on the Likert scale) than by paraesthesias (2,56) or joint pains (2,68) and most of all by depressive mood (2.96) and excitability (3.38). 4 patients (16%) had kidney stones, while osteoporosis and osteosclerosis occurred in 7 (28%) respectively 3 persons (12%). 6 patients (24%) had cataracts and 3 (12%) had basal ganglia calcification. Interestingly, 1/3 of all patients had only non-characteristic symptoms of the disease consistent with a latent form of hypoparathyroidism. CONCLUSIONS: Our data partly show a severe form of hypoparathyroidism of very young persons in the Chernobyl region, a finding which strongly supports the need of exact diagnosis and interdisciplinary treatment options of this postoperative disorder.