A left-sided interposition graft (modified Blalock-Taussig anastomosis) was constructed with polytetrafluoroethylene in a three month old child with tetralogy of Fallot. This shunt thrombosed and a replacement shunt became the site of chronic Pseudomonas infection. The second anastomosis was excised and a third interposition graft was inserted on the right side because the anatomy was unsuitable for a classical Blalock-Taussig shunt. The patient died when he was 12 months old, after signs of infection and shunt occlusion had developed. At necropsy the acutely thrombosed right sided shunt was found to be the site of Candida albicans infection. Gallium and labelled white cell scans, computed tomography, and ultrasound scans had all failed to identify the sites of infection, which were only confirmed at operation or necropsy.