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 observ ations, we have investigated the propagation of these photons in the therma l 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 futu re observations with the INTEGRAL observatory.