Acute kidney injury (AKI) has been described as a common complication of cardiac surgery in pediatric patients, whose impact on morbidity and mortality has been documented. Its incidence has been estimated to be approximately 40 % in this patient group. The objective of this study was to estimate the incidence of AKI in patients who underwent cardiovascular surgery and to define associated risk factors and the impact of AKI on the parameters of the postoperative course. This was a retrospective, observational study of pediatric patients who underwent cardiovascular surgery between January 2015 and December 2017 at Hospital Británico de Buenos Aires. The incidence of AKI was defined as per the Kidney Disease: Improving Global Outcomes criteria, based on pre- and post-operative blood creatinine levels and urine output. A total of 125 patients were included. Of them, 35 % developed AKI. The analysis of risk factors showed a statistically significant difference for the administration of vancomycin and thiazide diuretics, red blood cell transfusion requirement, extracorporeal circulation pump time, clamp time, maximal intraoperative lactate level, minimum temperature, and delayed chest closure. In relation to the parameters of the post-operative course, we observed a longer hospital stay, higher inotropic requirement, more days of mechanical ventilation, bleeding, and neurological complications. In this study, the incidence of AKI was 35 %. Modifiable and non-modifiable associated risk factors were defined and a greater rate of complications was observed in patients who developed AKI.