The problem of determining the effect of the media interface in a piecewise-homogeneous body on the stress concentration in the vicinity of cracks located in one of the half-spaces is reduced to a system of two-dimensional singular equations of Newtonian potential type. We study the effect of the relations of the elastic constants of the materials of a body composed of two half-spaces on the stress intensity factors in the vicinity of a crack. We study different variants of the crack location relative to the interface.The relations between the elastic constants of the materials of a piecewise-homogeneous body have a strong effect on the stress concentration in the vicinity of cracks located in the body. These problems are mathematically quite complicated and cumbersome, as shown by the limited amount published on them. A piecewise-homogeneons body composed of two half-spaces is the simplest object for which it is possible to study the effect of the relations between the elastic constants of the materials on the stress concentration in the vicinity of cracks.Suppose an infinite piecewise-homogeneous body composed of two half-spaces contains in its lower halfspace a system of N planar cracks, arbitrarily situated. The surfaces of the cracks are subject to given selfbalancing external forces N/., j = 1, 3, n = 1, N. Here NI. and N2. are the shears, and N~. are the normal external forces prescribed on the n th crack. The upper half-space is characterized by its Poisson coefficient v t and its shear modulus G~. The lower half-space, weakened by the system of N cracks is characterized by the respective elastic constants v 2 and G 2 .To solve the problem of determining the stress concentrations in the vicinity of the cracks we choose a basic Cartesian coordinate system OXIoX2oX30 in such a way that the xtoox2o-plane coincides with the interface between the media. We also prescribe local Cartesian coordinate systems Oxl.x2.x3. with origin O. in the region S., n = 1, N, occupied by the nth crack so that the x~.O.x2.-plane coincides with the region of the crack S.. When this is done, the opposite faces of the cracks S. ~ correspond to the values x3. = _+0. The locations of the cracks in the lower half-space are defined by giving the distances between the origins of the coordinate systems, the direction cosines ej0 . , ej,,0, j = 1,---3, n = 1, N, of the vector d.0 joining the points O. and O (Fig. 1), and the direction cosines of the axes of the local coordinate systems O.xj. in the Ox~oX2oX3o coordinate system, which are given by Table 1.The external loads producing a strain on the piecewise-homogeneous body under consideration cause a mutual displacement of the opposite faces of the cracks. These displacements are characterized by functions ctj., j=l, 3, n=l,N. In the process of reducing the problem of determining the stress-strain state of this body with cracks to boundary integral equations it is necessary to have a solution that makes it possible to satisfy the boundary