Costello syndrome is an extremely rare genetic disorder with growth delay after birth and typically results in short stature during childhood. It is one of the RASopathy of Ras/MAPK pathway syndromes. It affects the transforming protein p21, an enzyme that in humans is encoded by the HRAS gene and this case report described the congenital valvular pulmonic stenosis and ventriculomegaly associated with Costello syndrome by Transthoracic echocardiographic imaging in a 9-year-old boy.