Aneurysmal dilatation of the sinus of Valsalva is a rare structural cardiac abnormality in children. It appears to be more common in Asia. It may be clinically silent for many years but these defects frequently coexist with other cardiac malformations, causing, when rupture occurs, unexpected symptoms that are not explained by the original defects. We report a case of ruptured aneurysm of the sinus of Valsalva in a 12-year-old boy diagnosed with ventricular septal defect in the neonatal period with an uneventful course. The boy suddenly developed acute prechordal pain, symptoms of low heart output and systolic-diastolic murmur. The diagnosis of ruptured aneurysm of the sinus of Valsalva was based on echocardiography. Surgical treatment was required to close the ventricular septal defect and repair the aorta, without valvular replacement. The postoperative course was uneventful. We conclude that is extremely important to have a degree high suspicion of this entity in previously asymptomatic children, with or without cardiac anomalies, who suddenly present this kind of heart failure and abrupt changes in cardiac auscultation.