Efficiency of the combined prophylaxis and treatment of a diffuse goiter by preparations of sele- nium and iodine at 54 patients--men at the age of 41-50 years with the diagnosis of a diffuse goiter of 1st and 2nd degree was investigated. The diagnosis of a diffuse goiter was based on palpatory and ultrasonic research of the thyroid gland, which volume was compared with a body surface area. All surveyed have been divided into three groups. Patients of the first group accepted preparations of selenium and the iodine throughout three months, the second group--iodine preparations, in control group only dynamic supervision was spent. Thyroid gland volume at men who constantly used iodated salt and had no palpatory signs of a goiter was also measured for control. In the group which members accepted selenium and iodine preparations, at 11,8 % of patients was noted reduction of thyroid volume to normal and was revealed more expressed reduction of thyroid volume (for 2.15 sm3/M2 ± 0.07 sm3/M2), than at monotherapy by iodine preparations (for 0.92 sm3/M2 ± 0.17 sm3/M2). The conclusion was made that it is possible to recommend selenium preparations in a dose of 100 mkg a day together with preparations of iodine for prophylaxis and treatment of a diffuse goiter in conditions of the combined insufficiency in consumption of selenium and light deficiency of iodine.