Although surgery may correct the hemodynamic abnormalities of tetralogy of Fallot (TOF), the long-term effects on exercise tolerance are uncertain. Twenty-eight patients, aged 7 to 30 years, had cardiac catheterization and maximal graded exercise testing to evaluate the adequacy of the ehmodynamic repair and its relation to exercise performance. Patients were tested 2 to 9 years after operation, and 13 previously had had palliative shunt procedures. At catheterization, 23 of the 28 patients had good surgical results. Despite the satisfactory hemodynamics, maximal working capcity (MWC), maximum heart rate, and exercise blood pressure were diminished when compared to normal values. In 10 patients who had exercise studies at catheterization, right ventricular systolic pressure (RVSP) and residual gradients were magnified by exercise. Abnormalities were independent of age at time of correction, time elapsed since surgery, use of patch in the outflow tract, or any antecedent procedures.