The effect of recombinant human erythropoietin (rHu-EPO) on anaemia and some biochemical parameters was investigated in 7 predialysis patients. A statistically significant increase in erythrocyte, haematocrit and haemoglobin levels was observed after 3 weeks of treatment and such changes were constant during the 6 month maintenance therapy. The mean urea and creatinine levels were comparable during the tested period in 4 of the studied patients. The other 3 patients did not completed the planed period and started the dialytic therapy because of progression of renal insufficiency. The latter group had more advanced renal failure and higher blood pressure prior to rHu-EPO treatment as compared with the patients who completed the study.