Preoperative and postoperative pulmonary function tests and progressive work exercise performances were compared for fourteen pectus excavatum and five pectus carinatum patients who underwent operative repair. No changes could be documented in the pectus carinatum patients. The excavatum patients demonstrated a small improvement in total lung capacity (P less than .02) and a significant improvement in maximal voluntary ventilation (P less than .001). In addition, the exercise performances were improved for the excavatum patients postoperatively as quantitated both by the total exercise time and the maximal oxygen consumption (P less than .01). In addition, at any given work rate, the excavatum patient demonstrated a lower heart rate and higher minute ventilation after operation. These findings support the hypothesis that both the restricted cardiac stroke volume and the increased work of breathing that have been described in pectus excavatum patients can be ameliorated by operative intervention.