Uniform plastic slip is assumed to occur in a cubic region embedded at the free surface of a semi-infinite elastic solid. The slip plane and slip direction are both inclined at 45 deg to the free surface and to two opposite interior faces of the cube. The stress field produced by the slip is the same as that produced by equivalent uniform tractions acting on the faces of the cube. Closed-form solutions are obtained for all stress components by employing Papkovitch functions to calculate the effects of the equivalent surface tractions. Calculated numerical results for the distribution of stress components are shown graphically. Certain stress components are found to be discontinuous across the boundary surface of the region of plastic slip.