Pseudoaneurysm of the right ventricular outflow tract (RVOT) has been reported as a rare complication of RVOT reconstruction performed using conduit replacement or patch repair. The RVOT needs to be followed up on echocardiography and if aneurysm a large aneurysm forms, it needs to be operated. Usually progression of aneurysm is slow. Rarely, it may present with symptoms secondary to the compression of adjoining mediastinal structures or thrombus formation inside the aneurysm. We report two cases of rapidly progressing massive RVOT aneurysm needing early surgical intervention. Both patients had ventricular septal defect (VSD) closure and right ventricle to pulmonary artery conduit placement. In both patients Contegra pulmonary valved conduit (Medtronic) had been used.