Objective: To determine whether pectus excavatum (PE) results in cardiopulmonary abnormalities, and whether surgical repair results in improvement. Methods: We performed pulmonary function testing and incremental exercise testing in 36 adolescents with PE (aged 16 +/- 3 (SD) years) and 10 age-matched, healthy control subjects, Fifteen PE subjects were reexamined postoperatively, as were six control subjects. Results: Preoperatively, PE subjects had a significantly lower forced vital capacity than control subjects had (81% +/- 14% vs 98% +/- 9% of the predicted value; p < 0.001), Chest computed tomography ratios of internal transverse to anteroposterior diameters correlated inversely with total lung capacity (r = -0.56 p < 0.01), Fifty-eight percent of PE subjects had subjective complaints of exercise limitation, PE subjects exercised at a workload similar to that of control subjects, Maximal heart rate and O-2 pulse did not differ between the two groups, Respiratory measurements during exercise were similar between the two groups, Postoperatively there was no change in forced vital capacity (as a percentage of the predicted value), The PE subjects exercised for a slightly longer period and had a slightly higher O-2 pulse, whereas control subjects showed no change. Conclusion: Some subjects with PE have mild restrictive lung disease, which is not affected by surgical repair, Postoperatively they have a slight increase in exercise tolerance and O-2 pulse, which suggests improved cardiac function during exercise, However, the clinical implications of this modest improvement are unclear.