We describe a case of 17-year-old Chinese girl referred to our Pediatric Cardiology Unit for asthenia, reduced exercise tolerance, and dyspnea. Past medical history was relevant for multiple chest pain episodes in childhood and several syncopal episodes, for which the patient had been never evaluated. Clinical examination, electrocardiogram, and echocardiography were compatible with Williams–Beuren syndrome; such condition was later confirmed by genetic analysis. Cardiac magnetic resonance imaging showed transmural fibrosis of the apex with impaired left ventricular ejection fraction (29 %), severe stenosis of aortic sinotubular junction with left and right coronary ostia involvement; more importantly, the whole coronary artery tree beyond ostia was affected by multiple stenosis and aneurysmatic tracts. Ascending aorta proved hypoplastic, with post-stenotic dilation and multiple aneurysms. At the end of the diagnostic process, surgical risk was considered too high to proceed with the correction. The presented case is of educational value since it provides good iconographical illustration of diffuse, multiple-site coronary artery tree involvement, a rather rare co-morbidity in Williams–Beuren syndrome.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-015-1231-0) contains supplementary material, which is available to authorized users.