Between 1967 and July 1982, 1103 operations were performed for the tetralogy of Fallot of all types with 116 (10.5%) hospital deaths. Eighty-eight hospital deaths (10.5%) occurred in the 836 patients undergoing repair. The incremental risk factors for hospital death after repair include pulmonary arterial problems (p = 0.0002), major associated cardiac anomalies (p less than 0.0001), small size (young age) (p less than 0.0001), and more than one previous operation (p = 0.0004). Absent pulmonary valve is a risk factor (p = 0.04). In patients with pulmonary stenosis, the hospital mortality has decreased with time (p = 0.08), but the incremental risk of a high hematocrit (p = 0.0003) and of transannular patching (p = 0.05) has persisted. In the current era, the risk of repair in patients with pulmonary stenosis is estimated to be 1.6% (70% confidence limits [CL] 0.7% to 3.5%) at age 5 years, and at age 12 months to be 4.1% (CL 2.7% to 6.3%) without a transannular patch and 7.7% (CL a5.3% to 11%) with one. When pulmonary atresia is present, the probability of hospital death after repair when a valved extracardiac conduit is used is estimated to be lowest (5%; CL 2% to 8%) between 5 1/2 and 16 years of age. No deaths occurred among 53 patients with pulmonary stenosis receiving a primary palliative Blalock-Taussig or Gore-Tex shunt, and six deaths (12%) occurred in 51 patients with pulmonary atresia. Serious interim complications (sudden death, brain abscess) after these shunts occurred in two (1.9%; CL 0.6% to 4.5%) of the patients operated on. No iatrogenic pulmonary arterial problems have been recognized. Protocols based on these results are presented. Many of these selective recommendations may become unnecessary if the damaging effects of cardiopulmonary bypass are overcome by future research.