Objective: Acute kidney injury (AKI) is a frequent complication of cardiac surgery with cardiopulmonary bypass (CPB). The aim of this study was to determine the incidence of renal replacement therapy (RRT) requirement in children undergoing surgical repair for congenital cardiopathies and identify the risk factors for requiring RRT. Patients and Methods: A retrospective, descriptive study was performed. The records of patients under 18 years undergoing cardiac surgery with CPB (January 2001 to July 2008) who required RRT (n = 15) and from a random patients sample that did not require it (n = 57) were analysed. Results: Fifteen children out of 942 required acute RRT (1.6%). Initial RRT was peritoneal dialysis (PD) in all of them. The main indications were hypervolemia and/or oligoanuria. Ten patients experienced complications associated to therapy and 14 patients had a history of serious intraoperative events. In multivariated analysis, hypotension (OR 36.0, CI 95%: 5.5-235.6) and serious low cardiac output (LCO) (OR 14.1, CI 95%: 1.47-135.32) were significant risk factors for RRT requirement. In turn, the presence of intraoperative events was significantly associated with the occurrence of hypotension (OR 28.9, CI 95%: 3.6-233.9) and LCO (OR 5.3, CI 95%: 1.126.6) during the post-surgical evolution. Conclusion: In this experience, severe hypotension and low cardiac output were significant risk factors for RRT requirement. The incidence of RRT was 1.6%. Renal function should be closely evaluated in those patients with surgical events. RRT should be early considered in those patients with risk factors for renal failure.Introducción: La insuficiencia renal aguda es una complicación frecuente de la cirugía cardíaca con circulación extracorpórea (CEC). Objetivo: Determinar la incidencia de requerimiento de terapia de reemplazo renal (TRR) en niños sometidos a reparación quirúrgica de cardiopatías congénitas, caracterizarlos e identificar factores de riesgo de requerir TRR. Pacientes y Método: Se realizó un estudio retrospectivo descriptivo con un componente analítico. Se revisaron las fichas clínicas de los pacientes menores de 18 años sometidos a cirugía cardíaca con CEC (enero 2001 a julio 2008) que requirieron TRR (n = 15) y de una muestra aleatoria de pacientes que no la requirieron (n = 57). Resultados: De los 942 niños operados, 15 requirieron TRR aguda (1,6%). En todos, la TRR inicial fue peritoneodiálisis (PD). Las principales indicaciones fueron hipervolemia y/o oligoanuria. Diez pacientes presentaron complicaciones asociadas a la terapia y 14 tenían antecedentes de incidentes intraoperatorios graves. En forma multivariada, la hipotensión arterial (OR 36,0 IC 95%: 5,5-235,6) y el hipodébito grave (OR 14,1 IC 95%: 1,47-135,32) fueron factores de riesgo significativos de requerir TRR. A su vez, la presencia de incidentes intraoperatorios se asoció significativamente al desarrollo de hipotensión (OR 28,9 IC 95%: 3,6-233,9) e hipodébito (OR 5,3 IC 95%: 1,1-26,6) durante la evolución post-quirúrgica.