Williams' syndrome (WS) is a rare genetic condition of autosomal dominant inheritance with varying penetrance, which consists of supravalvular aortic stenosis, a characteristic dysmorphic facies named "elf face", mental retardation and other clinical manifestations including transient infantile idiopathic hypercalcemia, growth retardation, and frequent dental problems. It usually presents sporadically, and there are only a few cases of family involvement reported in the literature. Recent studies show that mutations in the elastin gene at chromosome 7q11.23, which occur approximately in 90% of cases, could be the cause of the different clinical manifestations in this syndrome. In this paper we report a case of family involvement with five family members involved with WS (three siblings, the mother, and the siblings' maternal uncle) and all had cardiac structural disorders (supravalvular aortic stenosis being the most frequent), a characteristic face and a low intellectual coefficient. The complementary tests included blood chemistry, chest X-ray, and echocardiogram, which led to the diagnosis of the associated valve pathology. Three patients required therapeutic catheterism with Stent valve implant and valve prosthetic replacement to control cardiac manifestations.