The diagnostic criteria of the Williams‐Beuren syndrome (WBS) were established almost 3 decades ago. Until now there has been little knowledge about the natural and post‐surgical history of vascular lesions in this syndrome. In order to evaluate the long term follow‐up of aortic and pulmonary vascular lesions, we have analysed the catheterization data, angiocardiograms, and Doppler‐echo measurements in 59 patients who were seen at least twice in our institution between 1961 and 1993. Their follow‐up periods ranged from 2.1 to 28.2 years. Of 45 patients with supravalvular aortic stenosis (SVAS) with a mean follow‐up period of 12.9 years, it became evident that pressure gradients of less than 20 mm Hg in infancy generally remained unchanged during the first two decades of life. Pressure gradients exceeding 20 mm Hg increased from an average of 35.5 mm Hg to 52.7 mm Hg in 13 patients. Of these, 8 required surgical relief of the narrowing. In 7 patients aortic hypoplasia was documented. In 5 of them the caliber of the aorta showed a tendency towards normalisation within a period of 11.9 to 23.9 years. Of 6 individuals with aortic hypoplasia and surgical relief of SVAS, 4 patients developed restenosis at the distal end of the aortoplasty patch. In contrast, 9 patients with operated SVAS—but without aortic hypoplasia—remained free of restenosis over a period of 11 years (mean). Coarctation occurred in 4/59 patients; restenosis was seen in 2 after 5 and 16 years. Peripheral pulmonary stenosis was followed in 23 patients over 14.4 years (mean). During this period the systolic pressure gradients fell from 23 to 9.3 mm Hg (mean). In adolescence and adulthood the gradients were below 20 mm Hg in 22/23 individuals.

In WBS there is a good long‐term prognosis for SVAS if gradients during infancy are low. SVAS with gradients above 20 mm Hg tend to increase; 60% of them require surgical relief with good long‐term results. But aortic hypoplasia impairs the prognosis of operated SVAS, because restenosis may occur. Peripheral pulmonary stenosis generally shows a good long‐term prognosis. © 1994 Wiley‐Liss, Inc.