Ethylene-vinyl acetate (EVA) copolymer functionalized with mercapto groups (EVALSH) has been used as compatibilizing agent in nitrile rubber/EVA blends. The tensile strength and elongation at break of the system were measured as a function of the EVALSH content and blend composition. The compatibilization affects the mechanical properties of these blends. The highest improvement of the tensile strength has been achieved in the composition range corresponding to the co-continuous phase morphology. The co-continuity of these blends has been studied by both dissolution studies and scanning electron microscopy. The addition of EVALSH as an interfacial modifier did not change the region of co-continuity but influences the percolation threshold for both dispersed nitrile rubber phase and dispersed EVA phase. From optical microscopy and differential scanning calorimetry analysis, it is possible to assume that the functionalized EVALSH copolymer affects the crystallization of the EVA phase.