Background: Acute kidney injury (AKI) is common in infants after cardiopulmonary bypass and is associated with poor outcomes. Peritoneal dialysis improves outcomes in adults with AKI after bypass, but pediatric data are limited. This retrospective case-matched study was conducted to determine if the practice of peritoneal dialysis catheter (PDC) placement during congenital heart surgery is associated with improved clinical outcomes in infants at high risk for AKI. Methods: Forty-two infants undergoing congenital heart surgery with planned PDC placement (PDC+) were age-matched to infants undergoing similar surgery without PDC placement (PDC-). Demographic, baseline and outcome data were compared. Our primary outcome was negative fluid balance on postoperative days 1 to 3. Secondary outcomes included time to negative fluid balance, time to extubation, frequency of electrolyte corrective medications, inotrope scores, and other clinical outcomes. Results: Baseline data did not differ between groups. The PDC+group had a higher percentage of negative fluid balance on postoperative days 1 and 2 (57% vs 33%, P = .04; 85% vs 61%, P = .01). The PDC+group had shorter time to negative fluid balance (16 vs 32 hours, P<.0001), earlier extubation (80 vs 104 hours, P = .02), improved inotrope scores (P = .04), and fewer electrolyte imbalances requiring correction (P = .03). PDC-related complications were rare. Conclusions: PDC use is safe and associated with earlier negative fluid balance and improved clinical outcomes in infants at high risk for AKI. Routine PDC use should be considered for infants undergoing cardiopulmonary bypass. Further prospective studies are essential to prove causative effects of PDC placement in this population.