We have assessed the clinical results and angiographic pulmonary artery growth following construction of the right ventricular outflow tract in 10 children with tetralogy of Fallot or pulmonary atresia. All cases were associated with diminutive pulmonary arteries and considered unsuitable for total corrective surgery. The mean age of the children was 34 months, mean weight 10 kg and mean body surface area 0.48 m2. The right ventricular outflow tract was constructed by insertion of a patch of dura mater (5 patients), pericardium (2 patients), homograft valved conduit (2 patients) and infundibulectomy (1 patient). The ventricular septal defect was not closed. Study of the patients between 13 and 37 months postoperatively revealed an increase in mean arterial oxygen saturation of 22% (P less than 0.01) and a fall in mean haemoglobin concentration of 1.6 g% (P less than 0.05). Overall change in pulmonary artery diameter compared to that of the trachea was insignificant although in individual cases a 50% increase in diameter was shown. Palliation of symptoms was equivalent to conventional shunting procedures. Closure of the ventricular septal defect was performed successfully in 2 patients at a later date.