Objective: The Main objective of the study was to evaluate the outcome of cardiac catheterization performed in the early postoperative period after congenital heart surgery. Background: Cardiac catheterization after congenital heart surgery may play an important role in the diagnosis and management of patients with complicated or unusual unexplained post-operative course. Methods: All patients underwent cardiac catheterization < 5 weeks after congenital heart surgery from November 2015 to May 2018 in pediatric cardiac center of King Abdul-Aziz University Hospital (KAUH) were included in the study. Results: Thirty procedures were performed for 27 patients (20 interventional and 10 diagnostic). The median age of the patients was 15 months (15 days to 20 years), weight 8.2 kg (3.4 to 53 kg), and time from surgery was 3 days (0-32 days). Eleven procedures performed for 11 patients on extracorporeal membrane oxygenation (ECMO). The main indications for catheterization were inability to wean from ECMO (10 procedures) and cyanosis (10 procedures). Interventional procedures were: Angioplasty using stents (10 procedures, success 90%), angioplasty using only balloons (2 procedures, success 50%), and occlusion for residual shunts (8 procedures, success 100%). No mortality was recorded during procedure. Procedural complications were recorded in 3 procedures. Survival among patients was 51.8%. There was no significant difference between interventional and diagnostic group regarding procedural complications. Patient on ECMO support had higher mortality than other patients. Conclusion: Cardiac catheterization could be performed safely in the early postoperative period; it could affect the outcome that is mostly dependent on complexity of cardiac lesions.