Nowadays in the Netherlands river dikes sometimes are strengthened with structural elements like sheet pile walls etc. At present a project is carried out to determine inundation risks of so-called dike rings. This requires calculation of the failure probabilities of the dikes from which these dike rings consists. In this paper a method is presented to calculate on a comparatively quick and easy way an estimate of the failure probability of a river dike strengthened with structural elements. The method makes use of the PLAXIS finite element model, particularly the so-called Phi/C reduction option for the calculation of safety factors. In this paper theoretical background and a practical example are described.