Postoperative acute renal insufficiency after cardiac surgery in neonates is associated with increased mortality and is usually treated (while using ECMO, extracorporeal membrane oxygenation) with hemofiltration. Renal support has to be continued after weaning from ECMO when oliguria persists. When using hemofiltration, prolonged anticoagulation and a vascular access is needed, which, however, carries the risk of hemorrhagic as well as thromboembolic complications. Alternatively, peritoneal dialysis (PD) can be performed. We report data from 5 infants treated with ECMO after corrective cardiac surgery, who experienced oliguria after ECMO weaning and were consequently treated with PD. Arterial and central venous pressures, inotropic demand, urinary output, blood urea nitrogen, creatinine and survival were investigated. All patients survived. Installation of PD resulted in stable hemodynamics in all patients, despite continued oliguria. Normal renal function was established in four patients. One patient, suffering from persistent renal insufficiency, remained on PD. PD effectively supports insufficient renal functioning after ECMO weaning without the need for anticoagulation or a vascular access. Acute renal insufficiency may be reversible even after weeks and, if necessary, PD also enables prolonged treatment until renal transplantation.