One of the main propagation effects on interference between adjacent Earth-space paths is considered to be the differential rain attenuation. In the present paper a method to predict differential rain attenuation statistics, valid for single-site communication systems, is extended to include double-site interfered systems operating under the dual-polarization mode. The extended procedure is again based on a model of convective rain cells as well on the lognormal model for point rainfall rate statistics. Numerical results are presented referring to realistic diversity systems operating under the hypothesis of using both single and dual polarization and suffering from differential rain attenuation. Some very useful conclusions are deduced on the reliable and economic design of future communication systems where orbital and frequency congestion are quite expectable. ¿ 1999 American Geophysical Union