The large-scale solar wind interaction with the Venusian ionosphere is numerically simulated in the framework of two-component, three-dimensional magnetohydrodynamics (MHD). The finite volume total variation diminishing scheme is used to solve this problem. The impinging solar wind is represented by H+ ions, and the ionosphere is assumed to consist of O+ ions produced by photoionization of atomic oxygen in the Venusian upper atmosphere and by charge exchange of CO2+ ions. The O+ ions are lost by charge exchange with carbon dioxide molecules. The numerical simulations are performed for an interplanetary magnetic field (IMF) perpendicular to the solar wind flow and for the solar wind parameters which correspond to maximum solar activity. Results of the calculation give the formation of the bow shock, the magnetic barrier, and the ionopause in the dayside region as a self-consistent state of the interaction processes. The dynamical behavior of the dayside ionosphere under the influence of the impinging solar wind and the IMF slipping over the pole results in the formation of wing-like bulges of the ionosphere and an accompanying poleward flow in the topside ionosphere. The model also reproduces several features of the nightside ionosphere that are predicted by earlier theories and observations, including complex structures such as a flattened ionotail, tail rays, and ionospheric holes, as a continuation of the wing-like bulge. It is also shown that slow plasma flow in the ionotail and nonideal MHD process play important roles in the formation of the induced magnetotail of the planet.¿ 1997 American Geophysical Union