Aims & Objectives: The Risk Adjusted classification for Congenital Heart Surgery (RACHS-1), stratifies anatomic diversity into 6 categories based on age, surgery, and mortality. The aim of this work was to assess the RACHS as a predictor of outcomes in newborns within a postoperative cardiovascular intensive care unit (ICU). Methods: We collected the data in Fundación cardioinfantil, Colombia (2010-2022). Analysis of variance (ANOVA) was used to compare means of duration of stay in the ICU, extracorporeal circulation times (ECMO), and intubation times across different RACHS levels. Post hoc comparisons were conducted using Tukey's method. Logistic regression models (LRM) were used to analyze potential predictors [AUC: 0.75 and 0.82; Hosmer and Lemeshow goodness of fit (GOF) p>0.001]. Results: 923 neonatal hospitalizations were recorded in the ICU. 368 patients were included (RACHS-1 records). The mortality in these patients was 10.6%, higher in patients with RACHS 4 (41%) and 3 (30.8%). Neonates with a higher RACHS tended to spend more time in the ICU (p<0.001), with statistically significant differences between RACHS 4, 5, 6, and RACHS 2 (p<0.005). However, in the LRM, RACHS was not a predictor of prolonged ICU stay (p:0.54). Patients with RACHS 3, 4, and 6 had significantly longer orotracheal intubation (OTI) times compared to lower complexity groups RACHS 1 and 2 (p<0.005). However, RACHS did not emerge as a predictor of prolonged IOT (p: 0.62). A longer ECMO time was a predictor of prolonged IOT(ORa: 3.95; 95% CI: 1.26–13.3; p:0.02). Conclusions: In neonates, RACHS-1 is associated with longer stay in ICU and OTI. Keywords: intensive care, Cardiac surgery, congenital heart disease, hospital mortality