The purpose of this study is to analyze the immediate results of bidirectional cavopulmonary anastomosis (BCPA) and Fontan operations performed in adults, and to reveal the risk factors. During the years 1983-2010, 681 consecutive patients underwent BCPA or a Fontan operation. Fifty-three of 681 patients were more than 18 years of age. Twenty-nine adults underwent BCPA and 24 underwent a Fontan operation. Immediate results of surgical treatment were followed during the hospital period. The average number of exceeded 'operability' criteria by Choussat et al. [Choussat A, Fontan F, Besse P, Vallot F, Chauve A, Bricaud H. Selection criteria for Fontan procedure. In: Anderson RH, Shinebourne EA, editors. Pediatric Cardiology. Edinburgh: Churchhill Livingstone, 1977:559-566] was significantly higher in patients from the BCPA group compared to the Fontan group (1.3±0.8 vs. 0.9±0.7, P=0.034). Hospital mortality after BCPA in adults was 6.9% (2/29) and did not differ from children (7.1%, 19/268), P=0.634. Hospital mortality after Fontan operation in adults was 8.3% (2/24) and did not differ from children (11.9%, 43/360), P=0.419. The frequency of non-lethal hospital complications was higher in patients after a Fontan operation. Patients from the Fontan group more frequently developed arrhythmias and prolonged pleural effusions. Preoperative regurgitation at atrioventricular valves was an independent risk factor for hospital mortality and morbidity after a Fontan operation. BCPA and Fontan operations performed in adults are accompanied by good immediate results and considerably improves patients' condition.