Electrical stimulation of myelinated nerve fibers was analyzed, using point sources in a simple (homogeneous) volume conductor model and a dynamic model of mammalian nerve fiber properties. The stimulus conditions resulting in anodal block of a propagating action potential were calculated as a function of electrode position. Results were compared with those from an analytical approach, using a passive fiber model under steady-state conditions. In comparison to the range of stimulus amplitudes suitable for cathodal nerve fiber recruitment, anodal block appears to be restricted to a small range and - at small electrode distance - to depend on the position relative to nodes of Ranvier.