Children with congenital aortic stenosis have 'excessive' left ventricular hypertrophy with reduced resting systolic wall stress that allows for supernormal ejection performance. If aortic stenosis is uncorrected, this pattern persists until adulthood. The effect of removing the aortic pressure gradient on left ventricular hypertrophy and wall stress in children with congenital aortic stenosis is unknown. To test the hypothesis that removal of the stimulus for hypertrophy by aortic valve replacement or repair would normalize left ventricular mass and wall stress, we measured left ventricular ejection performance, wall stress, and contractile function in seven patients at cardiac catheterization before and 36 ± 7 months after surgical correction of congenital aortic stenosis. After aortic valve replacement or repair, the aortic valve gradient fell from 87 ± 12 to 7 ± 4 mm Hg, and peak left ventricular pressure fell from 187 ± 14 to 128 ± 8 mm Hg. Left ventricular ejection fraction decreased postoperatively from 86 ± 4% to 74 ± 4% (p < 0.001), whereas velocity of circumferential fiber shortening decreased from 2.15 ± 0.15 to 1.6 ± 0.11 (p < 0.002). Left ventricular mass remained unchanged preoperatively (121 ± 14 g/m2) and postoperatively (121 ± 16 g/m2), but wall thickness (h) decreased in relation to ventricular radius (r) (h/r = 0.55 ± 0.05 preoperatively, 0.36 ± 0.2 postoperatively; p < 0.001). Left ventricular end-systolic wall stress increased after surgery from 45 ± 12 to 96 ± 13, whereas mean stress increased from 174 ± 18 to 249 ± 26 dynes x 103/cm2. Contractile function assessed by the velocity of circumferential fiber shortening-end-systolic stress relation, did not change after aortic valve replacement or repair. We conclude that after aortic valve replacement or repair in children with congenital aortic stenosis, wall stress increases and ejection performance decreases toward normal.