Traditionally, all patients undergo cardiac catheterization before bidirectional cavopulmonary anastomosis (BCPA). The purpose of this study was to determine if preoperative catheterization is necessary when echocardiographic parameters appear favorable. A retrospective review was performed of all patients who underwent BCPA (n = 142) between February 1996 and May 2001. Echocardiographic criteria defining a favorable BCPA candidate included good ventricular function, moderate or less atrioventricular and semilunar valve regurgitation, absence of ventricular outflow tract obstruction, normal proximal branch pulmonary artery (PA) size, and low PA pressures estimated by PA band gradient or systemic PA shunt velocity. The median age at operation was 7 months (range: 2-11) and weight was 6.2 kg (range: 2.7-7.1). There were 73 unfavorable candidates. Patients with hypoplastic left heart syndrome (n = 23) and pulmonary atresia with intact septum (n = 15) predominated among the unfavorable group. All patients were catheterized. This provided additional information on PA pressures in 3 patients in the favorable group but did not defer operation or influence outcome (no mortality, prolonged pleural drainage, or longer intensive care department stay). All 3 patients are alive at a mean follow-up of 51 months. The 30-day mortality was 2% (4 of 151 patients), all in the unfavorable group. Overall, 20 patients (13%) required arterioplasty of PAs at the time of BCPA. BCPA can be performed with a low risk of morbidity and mortality in a wide range of patients. By using commonly acquired echocardiographic parameters, a low-risk subgroup of patients can be identified who can safely avoid preoperative cardiac catheterization.