In spite of early dialysis and supportive therapy, children with severe HUS have a high incidence of sequelae with chronic renal failure (CRF) and/or hypertension. Previous experience at this center has shown 66% of children with HUS developing CRF. Since a plasma factor deficiency has been postulated in the pathogenesis of this syndrome, we studied the acute and long term effects of PI in HUS. Six children (3 boys) 2-5 years of age with HUS were treated with peritoneal dialysis and PI. Mean dose of PI was 25 ml/Kg/day given for 2-7 days. All children had oligoanuria >24 hours (x̄ duration 15 days; range 2-30 days) and thrombocytopenia (lowest platelet count x̄ 17,500; range 8,000-40,000). Mean serum creatinine before dialysis was 6.2 mg/dl. Transient hyptertension was present in all the patients and two had evidence of multi-organ involvement. After the initial dose of PI, platelet count rose to >100,000 in x̄ 4 days and oligoanuria resolved in x̄ 10 days. Total duration of dialysis period was x̄ 12 days (range 3-30 days). At last follow up (x̄ 13 months) all six children have serum creatinine ≤0.8 mg/dl (estimated GFR >75 ml/min/1.73 m2) and only two have mild hypertension and proteinuria. These results suggest that judicious administration of plasma has a beneficial effect in HUS by accelerating recovery from the acute phase and improving its final outcome.