The closed or "Nuss" repair of pectus excavatum is widely accepted for correction of moderate to severe deformities. Patients typically report significant subjective improvements in pulmonary symptoms, and short and medium term evaluations (up to 2 years with the bar in place) suggest modest improvement to cardiac function but a decrease in pulmonary function. This study examined the effects at 3 months post-bar removal of closed repair of pectus on pulmonary function, exercise tolerance and cardiac function. Patients were followed prospectively after initial evaluation for operation. All patients underwent preoperative and post-bar removal evaluation with CT scan, complete pulmonary function and exercise testing to anaerobic threshold, as well as echocardiogram. Twenty-six patients have completed the follow up protocol. Preoperative CT index was 4.5 +/- 1.3, average age at operation was 13.2 years, and average tanner stage was 3.5 +/- 0.5. At 3 months or greater follow-up post-bar removal, patients reported an improvement in subjective ability to exercise and appearance (P < 0.05 by wilcoxin matched pairs). Objective measures of FEV1, total lung capacity, diffusing lung capacity, O(2) pulse, VO(2max), and respiratory quotient all showed significant improvement compared to preoperative values, while normalized values of cardiac index at rest did not (All values normalized for height and age, comparisons P < 0.05 by student's paired t test). These results demonstrate a sustained improvement in cardiopulmonary function after bar removal following closed repair of pectus excavatum. These findings contrast with results from previous studies following the open procedure, or with the closed procedure at earlier time points; the long term physiological effects of closed repair of pectus excavatum include improved aerobic capacity, likely through a combination of pulmonary and cardiac effects.