We describe the impact of cardiovascular pharmacologic support on peritoneal dialysis adequacy in 20 neonates who required postoperative renal replacement therapy following cardiopulmonary bypass exposure. Peritoneal dialysis was administered for 2.5 (2) days. Peritoneal dialysis creatinine clearance was 3.4 (2.1) ml/min/1.73 m(2) and ultrafiltration rate was 9.75 (10) ml/h. Residual creatinine clearance was 31 (26) ml/min/1.73 m(2). Peritoneal dialysis creatinine clearance appeared to be a function of dialysate flow up to 100 ml/h. No correlation was present between inotropes and vasopressors infusion and peritoneal dialysis creatinine clearance/ultrafiltration rate. LDH clearance was 0.59 (0.85) ml/min/1.73 m(2) and it did not appear to have a correlation with dialysate flow. Patients in-hospital mortality was 20%, significantly higher than overall neonatal population admitted to our ICU (4.8%, P=0.02). Peritoneal dialysis in neonates allows optimal ultrafiltration rate and adequate small solute clearance, irrespective of hemodynamic status or vasopressor support.