Pectus excavatum is a depression of the sternum and costal cartilages which may present at birth, or more commonly during the teenage growth spurt. Symptoms of lack of endurance, shortness of breath with exercise, or chest pain are frequent. Although pectus excavatum may be a component of some uncommon syndromes, patients usually are healthy. Evaluation should include careful anatomic description with photographs, radiography to demonstrate the depth of the depression, extent of cardiac compression, or displacement, measurement of pulmonary function, and echocardiography to look for mitral valve prolapse (in 15%) or diminished right ventricular volume. Indications for surgical treatment include two or more of the following: a severe, symptomatic deformity; progression of deformity; paradoxical respiratory chest wall motion; computer tomography scan with a pectus index greater than 3.25; cardiac compression/displacement and/or pulmonary compression; pulmonary function studies showing restrictive disease; mitral valve prolapse, bundle branch block, or other cardiac pathology secondary to compression of the heart; or failed previous repair(s). The developmental factors, genetics, and physiologic abnormalities associated with the condition are reviewed.