In adults with ventricular septal defects, death usually occurs from heart failure, severe arrhythmias, paradoxical embolism, or infective endocarditis. Ventricular septal defects account for about 10% of congenital heart disease in adults, and those with small septal defects have a better prognosis. Those with larger defects, if not treated surgically, tend to die of heart failure, severe arrhythmias, paradoxical embolism, or infective endocarditis before the age of 30 years, and patients with progressive increases in pulmonary vascular resistance and pulmonary arterial pressure, usually before the age of 20 years, can develop Eisenmenger syndrome. Patients with ventricular septal defects may be treated with surgical repair of the defect or transcatheter occlusion. Small defects with normal pulmonary artery pressures may be left untreated; however, when combined with aortic valve prolapse and insufficient closure, surgery should be performed even if the fractional flow is minimal. Patients with ventricular septal defects that are detected in adolescence should be treated surgically to improve survival. It is recommended that the patient be seen as soon as possible after detection to avoid delay.