We calculated the structure of water in contact with the MgO(100) surface by using the three-dimensional reference interaction site model (3D-RISM) integral equation theory. The spatial distributions of water oxygen and hydrogen over the surface unit cell are calculated and discussed. The water density profiles and the orientations obtained are in good agreement with computer simulations for the same model of the interface. The 3D-RISM approach shows considerable promise as a constituent of a self-consistent description of chemical processes at a metal oxide-water interface.