The interaction of eddies with seafloor topography can exert large systematic forces on ocean circulation. Using a statistical mechanics approach it is possible to obtain a parametrization of this effect (the Neptune effect) for application in large-scale ocean circulation models. Circulation of the western Mediterranean has been observed to follow a definite cyclonic path. Numerical models usually show good qualitative agreement for the large-scale circulation but show systematic deficiencies at a subbasin scale. We have tested the importance of the Neptune effect on the circulation of the western Mediterranean Sea. To perform this test, different numerical experiments on western Mediterranean circulation were done with and without eddy-topography interaction. As a first step we analyze the influence of the Neptune effect in an ideal western Mediterranean with closed straits. After these experiments the more realistic case of open straits is studied. All the experiments show that the Neptune effect may be a significant factor in the basin and subbasin scale circulation in the western Mediterranean Sea. ¿ American Geophysical Union 1994