The thyroid gland of 536 patients of a medical hospital in an iodine deficient area was investigated by ultrasound. According to the sonographic pattern and to the scintigraphic imaging the focal lesions were analysed as micro- or macrofollicular adenomas, autonomous adenomas, cysts and chalk. The prevalence of goitres was 37,7%. The prevalence of goitres was higher in women (45%) than in men (30%). Focal lesions could be observed in 27,6%, equally more often in women (36%) than in men (18,9%). The frequency of focal lesions increased with the age of the patients and with the volume of the thyroid gland. Autonomous adenomas were found three times more often in women than in men. Hyperthyroidism was only observed in patients with nodules larger than 4 cm in diameter. Sonographic screening examinations of the thyroid gland seem to be useful in all patients of a clinic of medicine because of the risk (25%) of iodine contamination by diagnostic measures.