This review describes the assessment of the aortic valve by echocardiography and also the roles that multidetector CT (MDCT) and cardiac magnetic resonance have to play as complimentary imaging modalities. It describes how to resolve apparent discrepancies in grading aortic stenosis and discusses the management of apparently moderate stenosis associated with cardiac symptoms or left ventricular dysfunction. The role of cardiac imaging including three-dimensional (3D) echocardiography and MDCT scanning in the preparation for transcatheter aortic valve implantation and during and after the procedure are described. While echocardiography remains the mainstay of imaging, 3D modalities, notably MDCT, are increasingly useful and a multimodality approach is likely to become established as routine clinical practice.