Tetralogy of Fallot is the most common cyanotic heart lesion and one of the most commonly seen by cardiologists caring for adults with congenital heart disease. In the last 50 years, the outlook for these patients has changed dramatically, and most children with tetralogy of Fallot will live well into adulthood. Although most will have undergone a corrective operation, an important minority of patients with tetralogy of Fallot will have had only a previous palliative procedure. Rarely, the clinician may encounter an adult with unoperated tetralogy of Fallot. With surgical correction, the very long-term outcome is excellent, and most patients lead active and productive lives. However, certain issues must be considered for the long-term care of patients with tetralogy of Fallot. These individuals have an important incidence of residual or recurrent lesions as well as an increased risk for late sudden death. The exact mechanisms for late sudden death are incompletely defined but probably include both the residual hemodynamic and electrophysiologic substrates that act in concert.