This study on blood levels of trace metals in hemodialysis patients was carried out with an aim to clarify the impact of hemodialysis therapy on the trace metals status in such patients. Two hundred sixty six hemodialysis patients were enrolled. All patients underwent standard hemodialysis. Blood was collected before and after hemodialysis sessions. Atomic absorption spectrophotometry was applied to measure blood levels of aluminum, lead, cadmium, mercury as well as plasma levels of copper, and zinc. Aluminum, lead, mercury, and cadmium level in blood significant by increased after hemodialysis. The patients treated with acetate hemodialysis had significantly higher blood aluminum levels than the patients treated with bicarbonate hemodialysis (38.4+/-44.6 versus 25.9+/-43.5 microg/l, p=0.03). We observed negative correlation between copper concentration (n=60) in plasma and ultrafiltration (r=-0.4, p=0.003). The zinc and cadmium level increased with dialysis duration (r=0.2, p<0.001; r=0.2, p<0.02). Low plasma zinc levels, that is, <800 microg/l, was more often found in patients with <12 hour/week and <12 months hemodialysis duration. After 3 years of dialysis treatment blood lead, cadmium level (n=30) increased and plasma copper level decreased.