The abnormal metabolism of macrominerals and trace metals, a frequently overlooked fact may be one of the factors influencing clinical disorders in chronic dialysis patients. The purpose of this study was to compare to what extent maintenance hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) therapy influences the magnesium (Mg) and zinc (Zn) levels in blood of patients treated by these two methods. Additionally, we examined the influence of rhEPO therapy on Hb concentration in erythrocytes, total protein and albumin levels in plasma, and possible impact of rhEPO on Zn and Mg content in blood. Seventy-five ESRD (25 treated and 15 non treated with rhEPO on HD), and (20 treated and 15 non treated with rhEPO on CAPD) patients participated in this study. Forty-five healthy volunteers (HV) served as a reference group. The mean plasma and erythrocytes Mg concentration (mmol/l) in HD and CAPD patients without and with rhEPO treatment was found to be significantly higher than in HV. In HD and CAPD patients treated by rhEPO the mean erythrocytes Mg levels were significantly lower than in non rhEPO treated groups. The inverse relationship between Hb and Mg concentration in erythrocytes in HD and CAPD patients with rhEPO treatment was observed (r = -0.63, P < 0.05 and r = -0.59, P < 0.01 respectively). The mean plasma Zn levels (micromol/l) in HD and CAPD patients with and without rhEPO have been significantly lower than in HV. In patients treated by rhEPO significant increase of Zn erythrocytes levels was found. We was found positive correlation between plasma and erythrocyte Zn levels and Hb concentration in HD and CAPD patients treated by rhEPO (r = 0.35, P < 0.05 and r = 0.4, P < 0.05 respectively). The Hb concentrations, total protein and albumin levels in HD and CAPD with rhEPO therapy were found significantly higher than in patients without rhEPO therapy, but still lower if compared to HV. Mean levels of iron and TIBC in plasma have been found significantly lower in both studied groups treated or non treated by rhEPO, in comparison to HV. In both studied groups of patients without rhEPO or treated by rhEPO plasma GC, GSA, Cr concentrations were significantly higher from those obtained in HV. No statistical correlations were found between Mg, Zn and total protein, albumin, iron levels and TIBC. During rhEPO therapy increased Hb concentration was connected with higher plasma and erythrocytes Zn levels and lower erythrocytes Mg levels. rhEPO may improve the Mg and Zn disturbed metabolism in uraemia.