Oxidative stress is at play in the progression of chronic renal failure (CRF) and in the genesis of atherosclerosis. The aim of the present study was to evaluate the factors that might influence the oxidative-antioxidative balance in patients on hemodialysis. The study group consisted of 71 hemodialysis patients due to CRF. Sixteen healthy subjects constituted a control group. The levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), C-reactive protein (CRP), and the blood lipid profile were measured in both groups. The results showed significantly higher mean levels of both 8-OHdG and CRP in the hemodialysis patients compared with that in the control subjects. The highest level of 8-OHdG was found in the subgroups of the patients with CRF primarily caused by diabetes (16.4 ng/ml) and with hypertensive nephropathy (15.8 ng/ml). More than a 2.5-fold higher level of 8-OHdG in the hemodialysis patients compared with the control subjects points to the presence of intensive oxidative stress in the patients.