Human recombinant erythropoietin was administered subcutaneously to 26 chronic haemodialysis patients over a six month period, and the effect of erythropoiesis investigated. Initial therapy was 4000 units twice weekly with therapy titrated to individual response after 1 month. Mean EPO dosage was 150 ± 51 u/kg/week at the start of the study and 112 ± 50 u/kg/week at 6 months. The mean haemoglobin level rose from 6.7 ± 1.7 gr/dl at the start of treatment to 9.1 ± 1.9 gr/dl at 3 months (p<0.01) and 9.6 ± 1.9 gr/dl at 6 months. Simultaneously the mean haematocrit rose from 21 ± 4.8 to 28.3 ± 6.2 at 3 months (p<0.01) and 29.3 ± 4.6 at 6 months. Platelet count and white cell count were unaffected by therapy. Treatment failure occurred in 5 patients and seizures were seen in 4 patients. EPO therapy was not associated with increase in blood pressure.