While Fontan operation is considered a palliative procedure for the treatment of complex congenital heart disease, its morbidity and mortality are certainly not negligible, especially in high-risk patients. In our opinion, a bidirectional cavo-pulmonary anastomosis with an additional source of blood flow to the lungs (Blalock-Taussig shunt, pulmonary artery banding, native pulmonary stenosis) represents a valuable surgical option in this subset of patients. From November 1992 to September 1994, sixteen patients with complex congenital heart disease underwent bidirectional cavo-pulmonary anastomosis, leaving an additional source of blood flow in place (modified Blalock-Taussig shunt in 9 cases, pulmonary artery banding in 6 cases, native pulmonary stenosis in 1 case). Eight of these patients (50%) were reinvestigated after a mean follow-up of 15.7 months (range 1-26 m). It has been possible to differentiate two types of pulmonary blood flow, according to the nature of the additional flow source; in the case of cavo-pulmonary anastomosis and pulmonary artery banding or pulmonary stenosis, pulmonary blood flow was pulsatile and evenly distributed to both lungs, while in the case of bidirectional cavo-pulmonary anastomosis and Blalock-Taussig shunt, pulmonary flow was non pulsatile and asymmetric (angiographic criteria). There were no hospital deaths. Late mortality was 12.5% (2 pts) due to worsening of atrioventricular valve regurgitation. In one of these two patients, prolonged pleural and pericardial effusion occurred. In conclusion, bidirectional cavo-pulmonary anastomosis with an additional flow source is a good alternative to classic or fenestrated Fontan operation in the treatment of complex congenital heart disease. The best results are obtained with an additional flow source represented by pulmonary artery banding or pulmonary stenosis, due to pulsatility and uniform distribution of blood flow in the pulmonary district. Morbility and mortality compare favorably with the rates observed in classic or fenestrated Fontan operation.