We analyse the measured critical current Im in a mesoscopic 4-terminal S/N/S structure. The current through the S/N interface is shown to consist not only of the Josephson component Ic sin ϕ, but also a phase-coherent part Isg cos ϕ of the subgap current. The current Im is determined by the both components Ic and Isg, and depends in a nonmonotonic way on the voltage V between superconductors and normal reservoirs reaching a maximum at V ∼ = ∆/e. The obtained theoretical resultas are in qualitative agreement with recent experimental data.Recent achievements in nanotechnology have revived interest in the study of nonequilibrium and phase-coherent phenomena in superconductor-normal metal (S/N) structures. One of the most remarkable, discovered recently [1], was the observation of the sign reversal of the Josephson critical current I c (the so-called π-junction) in a multiterminal mesoscopic Nb/Au/Nb structure under nonequilibrium conditions. By passing an additional current through the N layer or, in another words, by applying a voltage V to the normal reservoirs (see Fig.1) with respect to the superconductors, one can create a nonequlibrium electron-hole distribution, or at least one can shift this distribution with respect to the electron-hole distribution in the superconductors. Under this condition, the critical current I c decreases with V and changes sign at a certain value of the applied voltage V . This effect was predicted first in Ref.[2] where a ballistic 3-terminal structure was considered (for more details, see also Refs. [3,4]). In diffusive 4-terminal S/N/S structures, the sign-reversal effect has been considered in Refs. [5][6][7] (see also [8,9]). The sign-reversal effect and switching of the π-junction into a state where ϕ = π has much in common with an instability of an uniform superconductor with a nonequilibrium distribution function [10,11].In multi-terminal S/N/S structures one can observe not only the sign reversal effect, but also a number of other interesting phenomena. For example, the conductance of a normal wire between N reservoirs oscillates with varying phase difference ϕ (see review articles [12,13]). In addition, as shown in Refs. [5,14], the measured critical current I m depends on the geometry of a particular structure and instead of decreasing may also increase with increasing voltage V . In particular one can observe Josephson-like effects (plateau on the I 3 (V S ) curve, oscillations of the measured critical current I m in a magnetic field etc) even if the Josephson coupling between superconductors under equilibrium conditions is negligable. The reason for these effects is that the current I m in a multi-terminal S/N/S structure is determined not only by the Josephson component I c sin ϕ, but also by the phase-dependent subgap current I sg cos ϕ through the S/N interface. Therefore even in the case of a small I c , the current I m can be altered by varying the phase φ. An increase of the critical current was observed in the recent paper [15] where a mesoscopic three-terminal ...