Recent advances in the surgical treatment of congenital disorders of the heart have necessitated an accurate preoperative diagnosis. Right heart catheterization has become widely accepted as a research tool and diagnostic test to detect the heart diseases, especially in the congenital heart anomalies. Right heart catheterizations were carried out in 50 cases of congenital heart diseases at Department of Thoracic and Cardiovascular Surgery, , Kyungpook National University Hospital, during the period of June, 1975 through September 1978. In age distribution, 27cases were below 10 years of age, 18 cases between 11 and 20, and 5 cases above 20 male to female ratio was 2.8:1. The distribution of congenital heart diseases was VSD [42%], TOF [36%], PDA [10%], ASD [8%], and PS[4%]. Of these, 44 cases [88%], were compatible with the clinical impressions that were made preliminarily before cardiac catheterization, and all the cases except 1 case of VSD was correlated well with the postoperative diagnosis. The right heart catheterization is considered to be reliable and accurate toll in the preoperative diagnosis of congenital heart diseases. These procedures caused complications such as left side hemiplegia [lcase], occlusion of the femoral artery [lcase], and transient ventricular tachycardia [1case], and so the complication rate of right heart catheterization was 6% [3 cases]. None of patients who have undergone right heart catheterization was died.[KTCS 1978;4:523-528]