Bloodstream infections (BSIs) are a main cause of nosocomial infection in the critical care area. The development of BSI affects the surgical outcome and increases intensive care unit (ICU) morbidity and mortality. This prospective cohort study was undertaken to determine the incidence, etiology, risk factors, and outcome of BSI for postoperative pediatric cardiac patients in the pediatric cardiac ICU setup. All postoperative pediatric patients admitted to the pediatric cardiac ICU from January 2007 to December 2007 were included in the study. Data were prospectively collected using a standardized data collection form. Patients with BSI (group 1) were compared with non-BSI patients (group 2) in terms of age, weight, surgical complexity score, duration of central line, need to keep the chest open postoperatively, and the length of the pediatric cardiac ICU and hospital stay. Of the 311 patients who underwent cardiac surgery during the study period, 27 (8.6%) were identified as having BSI (group 1). The 311 patients included in the study had a total of 1,043 central line days and a catheter-related BSI incidence density rate of 25.8 per 1,000 central line days. According to univariate analysis, the main risk factors for the development of BSI after pediatric cardiac surgery were lower patient weight (p = 0.005), high surgical complexity score (p < 0.05), open sternum postoperatively (p < 0.05), longer duration of central lines (p < 0.0001), and prolonged pediatric cardiac ICU and hospital stay (p < 0.0001). Gram-negative organisms were responsible for 67% of the BSI in the pediatric cardiac ICU, with pseudomonas (28%) and enterobacter (22%) as the main causative organisms. The mortality rate in the BSI group was 11% compared with 2% in the non-BSI group. In our pediatric cardiac ICU, BSI developed in 8.6% of the children undergoing cardiac surgery, mainly caused by a Gram-negative organism. The main risk factors for BSI in the postoperative pediatric cardiac patient were high surgical complexity, open sternum, low body weight, longer duration of central line, and prolonged pediatric cardiac ICU stay.