Relationship between the low selenium concentration and malignant disease has been already described. As the incidence of malignancy in uremic patients is higher than in other populations, in the present study we have determined the selenium levels in dialysed patients. In order to obtain the normal values for our region, 202 healthy persons were examined. The mean selenium content for this group (66, 80+/-0, 13 micrograms/l) is among the lowest in Europe. Selenium was determined also in 16 nephrological patients without signs of renal insufficiency and their mean levels (63, 4+/-0, 7 micrograms/l) did not considerably differ when compered to the normal values. In 45 patients on maintenance hemodialysis the level of selenium (56, 0+/-11, 88 micrograms/l) was significantly lower in comparison with the concentration in normal subjects and nephrological patients. Concluding this study we can confirm that the values of selenium in dialysed patients are so low that we can recommend the peroral administration of selenium in case of the end-stage renal failure.