We analyzed 519 catheterization procedures performed over a period of two years retrospectively. Several risk factors related to the patient or catheterization were analyzed. The incidence of complications was 6.2%. The most common major and minor complications were arterial thrombosis that required intervention and transient arrhythmias, respectively. The incidence of complications during interventional studies was higher (9.7%) when compared to that in diagnostic procedures (5.4%). The independent risk of any complication was greatest up to 1 year of age (p = 0.02). The risks of a major complication (p = 0.003) and development of arterial thrombosis (p = 0.02) were significantly greater in patients <1 year of age by univariate analysis. The risks of pediatric cardiac catheterization continue to decline. The complication rates associated with interventional catheterization were significantly higher than with diagnostic catheterization in this study. Younger age, particularly <1 year of age, is the strongest predictor of development of any complication.