Because increasing numbers of patients with surgically repaired tetralogy of Fallot (TOF) are surviving to adulthood, this study was done to provide follow-up data for physicians concerned with their care. We reviewed the current status of 233 patients born before January 1962 who had repair ofTOF at a median age of 9.7 years (range 11 months to 36 years). There were 26 surgical deaths (11.1%), 12 late cardiacrelated deaths (5.9%) and three noncardiac deaths (1.3%). Eight of the 12 late deaths occurred suddenly and unexpectedly. In each of these eight patients we had previously documented elevated right ventricular systolic pressure as well as ventricular premature depolarizations (VPDs). Among the 95 patients who responded to a questionnaire, 84 denied symptoms, 28 were married, 44 had attended college and all were employed. Cardiac catheterization revealed an unsatisfactory hemodynamic result in 39 of 120 patients, 30 of whom were asymptomatic. The poor result was due to a large left-to-right ventricular shunt in eight patients, persistent right ventricular outflow obstruction in 25 patients, pulmonary vascular obstructive disease in five patients, and left ventricular cardiomyopathy in one patient. Among the 21 patients with VPDs, 17 underwent cardiac catheterization: 15 had a right ventricular systolic pressure > 60 mm Hg and all had elevated right ventricular end-diastolic pressure. We conclude that 1) clinical assessment alone is nonpredictive of the hemodynamic result and thus cardiac catheterization is indicated in all patients; 2) the combination of persistent elevation of right ventricular systolic pressure above 60 mm Hg and VPDs placed the patient at risk for sudden death; and 3) over 80% of adults with repaired TOF can lead a normal life without impairment of intellect, exercise tolerance or fertility.