Hemodynamic studies were made 2 weeks after repair of tetralogy of Fallot in 18 cases and 2 months to 6 years after operation in 5 cases. Intracardiac and intravascular pressures, oxygen uptake, arteriovenous oxygen content difference, cardiac output, heart rate, stroke index, and pulmonary and systemic resistance were measured. Residual intracardiac shunts and residual pulmonary stenosis and incompetence were assessed. Results were compared with similar studies on postoperative days 1, 2, and 3. Further insight into patterns of convalescence as well as into the favorable hemodynamic state usually pertaining after repair are provided by these data.