The recombinant human erythropoietin (rHuEPO) by subcutaneous route has been considered the drug of choice for the correction of the anemia of chronic renal patients. PURPOSE--To evaluate the efficacy of a new preparation of rHuEPO in the correction of the anemia of chronic renal patients maintained by haemodialysis, exclusively administered by subcutaneous route, studying the adverse effects and searching for predictive factors for the response to this medication. METHODS--Twelve patients in regular haemodialysis were treated with freeze-dried rHuEPO by subcutaneous route during 18 months with initial doses of 20U/kg/dialysis. They were submitted to a careful clinical and laboratory monitoring for all this study. RESULTS--Eleven patients ended the study reaching the target hematocrit (Htc) of 30% and keeping it during the whole period of the study. The mean correction and maintenance doses of rHuEPO were 65U/kg/dialysis and 51U/kg/dialysis respectively. At the 12th week of the study a significative increase of Htc (18.4 +/- 3.5% vs. 25.4% +/- 3.8%, p < 0.05) was demonstrated. An increase of the erythrocytes and hemoglobin was concomitantly observed. Leucocytes and platelets increased significantly from the 24th week and kept steadily until the end of study. Just potassium increased in the biochemistry analysis of the patients at the 4th and the 12th week of the study returning to the basal values at the 24th week. The evolution of the iron metabolism parameters demonstrated an intermitent and statistically significant decrease of transferrin saturation at the 1st, 12th and 24th week, returning to the basal levels at the end of study. The serum ferritin did not change (582.7 +/- 700, 9ng/mL vs. 700.0 +/- 651, 6ng/nL). The weight and the blood pressure did not change either, although 2 normotensive patients became hypertensive and 2 others with controlled hypertension needed drug rearrange for blood pressure control (36%). A patient had a seizure episode with a full recovery. CONCLUSION--The rHuEPO has proved to be a safe and an efficient drug with easily controlled adverse effect.