Gamma-rays from cascades in massive close X-ray binaries

Assuming that very high energy gamma-ray photons Or electrons are injected inside a massive close binary system, as suggested by some Cherenkov observations, we have investigated the propagation of these photons in the thermal anisotropic radiation of the massive star by using the Monte Carlo method. The results are discussed in the context of recent observations of gamma-rays from massive binaries (Cyg X-3, LSI 303 degrees, Cen X-3 and Vela X-1) made with the COMPTEL and EGRET detectors of the CGRO, and in view of future observations with the INTEGRAL observatory.