We observed Budd-Chiari syndrome in a boy aged 2 years 6 months with nephrotic syndrome due to hepatic vein and inferior vena cava thrombosis, confirmed by Doppler imaging. Normal values of the routine hemostatic parameters proved that they are of little predictive value for the thrombotic state. Immediate heparin infusion was initiated. High doses of heparin up to 59 IU/kg per hour were required for efficient anticoagulation. A remission of the nephrotic syndrome was achieved with vincristine. Oral anticoagulation with a vitamin K antagonist was continued for 6 months. Doppler imaging then indicated full re-establishment of the blood flow through the affected vessels. The clinical and Doppler data in this case are compatible with acute Budd-Chiari syndrome due to incomplete outflow obstruction of the hepatic veins and inferior vena cava. The favorable outcome was due to the immediate heparin infusion and prompt remission of the nephrotic syndrome. Doppler imaging was an important tool for non-invasive diagnosis and follow-up.