Extracorporal detoxication methods in newborns are most unavailable, contraindicated because of technical problems. Herein are reported the experiences with a blood pump unit that was miniaturized for hemodialysis, hemofiltration, and plasmapheresis in newborns. In three premature infants with acute renal failure of different etiology (two newborns with severe Rh-erythroblastosis, 1 premature infant with hypoproteinemia) 13 single-needle hemofiltrations and 6 single-needle plasmaphereses were performed with double head pump, special tube systems, and small modules. The age of the patients ranged from 1 to 14 days, body weight was between 800 and 2,800 g. Four umbilical veins and two femoral veins were used as vascular access. The ultrafiltration rate during the treatment averaged 0.3 ml/min in single-needle hemofiltration and the plasma filtrate flow rate 1.3 ml/min in single-needle plasmapheresis. All treatments were well tolerated. Four patients died due to complications unrelated to the treatment, two patients recovered. These preliminary results show that both hemofiltration and plasmapheresis may be carried out without major problems in premature infants and newborns.