  Consider binary system with a millisecond pulsar ejecting relativistic
particles and an optical star emitting soft photons with the energy $\omega
\simeq 1-10$ eV. These low-energy photons are scattered by the relativistic
electrons and positrons of the pulsar's wind. The scattered photons forms a
wide spectrum from hard X-ray band up to gamma band $\epsilon \simeq 1-1000$GeV
>.When the pulsar wind is isotropic the luminosity of gamma radiation $L_\gamma
=L_\gamma (\psi)$ depends heavily on the angle $\psi $ between the directions
to the optical star and to the observer from the pulsar. During the orbital
motion this angle varies periodically giving rise to the periodical change of
the observed intensity of the gamma radiation and its spectrum. We calculated
the spectral shape of the scattered hard photons. Under the assumption that the
energy losses of the relativistic particles are small we receive analytical
formulas. We apply our results to the binary system PSR B1259-63 and show that
if the wind from the Be star is accounted for then it is possible to reproduce
the observed spectrum.
