A semiconductor package includes a lower package including a lower semiconductor chip on a lower package substrate, an upper package on the lower package, and a heat interface material between the lower package and the upper package. The upper package includes an upper semiconductor chip on an upper package substrate including a center portion adjacent to the lower semiconductor chip and an edge portion. The heat interface material is in contact with a top surface of the lower semiconductor chip and the upper package substrate. The upper package substrate includes a heat diffusion via penetrating the center portion and an interconnection via penetrating the edge portion. The interconnection via is spaced apart from the heat diffusion via.