Introduction:Congenital heart diseases are the most common congenital abnormalities in newborns with a prevalence of 1%.Therapeutic and diagnostic cardiac catheterization has revolutionized the treatment of these diseases; however, it can be associated with complications.Objective: To describe the incidence and type of complications associated with pediatric cardiac catheterization in a reference center for congenital heart defects.Methodology: Retrospective observational study, with analytical intention based on records of cardiac catheterization, performed on patients with congenital and acquired heart disease.Results: Two thousand six hundred and eighty-eight records were included for nine consecutive years.About 53.9% were men, 21.3% with ages between 2 and 5 years, and 20.3% between 6 months and 2 years.About 63.5% of the procedures were elective.The prevalence of complications in the first 24 h after catheterization was 6.7% (4.2% minor and 2.4% major).Early death occurred in 0.8% of the procedures.Factors associated with complications were age at catheterization < 28 days (odds ratio OR 2.18, 95% Confidence Interval CI [1.28-3.70]),precatheter oxygen saturation < 79% (OR 2.15, 95% CI [1.02-4.53]),use of pre-catheter inotropics (OR 3.00, 95% CI [1.68-5.33]).The variables included in the model explain 38% of the variance of post-cardiac catheterization complications in patients younger than 18 years.Discussion: Cardiac catheterization is associated with major and minor complications including death.The associated factors were < 28 days, lower oxygen saturation, and use of pre-catheter inotropics.