This study is presented to identify and characterize the spectrum of the cardiovascular anomalies in children presenting with Williams-Beuren syndrome and cardiovascular anomalies at The Hospital for Sick Children, Toronto from 1966 to 1988. Forty-nine children were diagnosed and followed. The female to male ratio was 1.2∶1. The age ranged from 1 month to 14 years at the time of diagnosis (mean 39 months), and follow-up periods were from 9 months to 20 years (mean 10 years). All patients having the typical features were also evaluated by geneticsts. Based on cardiovascular findings four groups were identified. Group 1 had isolated supravalvular aortic stenosis (SVAS) (28 patients). There was follow-up in 24 of these children. Six had worsening of supravalvular narrowing and underwent surgery. One showed an increased gradient from 10–40 mmHg during 7 years. Seventeen had mild narrowing and showed no progression over a period of 75 months. Group 2 had isolated pulmonary artery branch stenosis (8 patients). Seven had mild narrowing which remained unchanged over a mean period of 16 months and one underwent surgery. Group 3 had combined lesions (11 patients). Six showed increased left-side narrowing, while right-side obstruction remained static or improved. Five showed improvement in narrowing in both outflow tracts. Five underwent surgery. Additional cardiovascular anomalies included peripheral artery stenosis in two patients, coronary artery abnormalities in three, mitral valve prolapse in three, and coarctation of the aorta in two. Group 4 had isolated lesions. One patient had isolated coarctation of the aorta and one isolated mitral prolapse. In conclusion, supravalvular aortic stenosis was the most common lesion, whereas pulmonary artery stenosis improved in most patients. The role of coronary artery abnormalities has yet to be defined.