In this paper fluid–structure interaction models of bioprosthetic or native aortic valves are proposed for the assessment of aortic stenosis severity. The fictitious domain approach is applied for the blood–valve interaction and the valve and root geometry are defined such that geometrical changes can easily be made. Clinically relevant scenarios are demonstrated using the models by introducing variable stroke volumes, differently shaped valve and root, leaflet fusion or calcifications. Systolic behaviour of the valves is observed and the severity of the occlusions is evaluated using the following clinically relevant criteria: geometrical orifice area, trans‐valvular pressure gradient, effective orifice area and Energy loss coefficient. Within this context, the benefits, shortcomings and potential of the presented three‐dimensional models are identified and discussed. Copyright © 2009 John Wiley & Sons, Ltd.