Propagation of an interplanetary shock along the heliospheric plasma sheet (HPS) is simulated using a high-resolution numerical MHD model in the meridional plane. The ambient solar wind contains two opposite orientations of the interplanetary magnetic field above and below the equatorial plane. These regions are separated by a thin transition layer that represents the heliospheric current sheet contained within the HPS. A pulse is introduced at the inner boundary (0.1 AU) into this steady state to initiate the interplanetary shock. The HPS with its weaker intensity of the magnetic field, larger mass density, and slower flow velocity modifies the global shock structure. A dimple is formed at the forward shock front, a reverse dimple is formed at the reverse shock, and the contact discontinuity is significantly distorted. Weak compression of the HPS occurs beyond the forward shock front due to the postshock increase of the azimuthal magnetic pressure. Although slight collimation of mass flow takes place toward the axis of the HPS, an antisunward protrusion (pimple) within the shock front's dimple did not form in our simulation.¿ 1996 American Geophysical Union