Ninety-six consecutive total repairs of the tetralogy of Fallot are reviewed. There was an overall hospital mortality of 8-3 per cent and a total incidence of low output cardiac failure of 18-8 per cent, and this was the principal cause of death and the most important source of postoperative morbidity. In 49 cases there had been a previous palliative shunt procedure and there was a strikingly lower mortality and a highly significant lower morbidity in this group. Other factors which correlated in a positive fashion with increased mortality and morbidity were chronic hypoxia (as evidenced by polycythaemia), age below 5 years, severe postoperative right ventricular hypertension, and (to a lesser extent) extensive right ventricular outflow tract reconstruction. Data are presented to support the hypothesis that a palliative shunt procedure should be considered in the severely polycythaemic child with a surgically 'unfavourable' right ventricular outflow. This policy carries a low early mortality in our hands (5-4%), and is associated with a low mortality (3-9%) at a subsequent repair. This compares with a mortality of 12-8 per cent for primary repair, and the incidence of low output cardiac failure is five times as high in the primary repair as compared to the previously shunted group.