  Several binary systems have been detected at High Energy (HE, E > 100 MeV)
and/or Very High Energy (VHE, E > 100 GeV) gamma rays. Some of them are X-ray
binaries in which accretion feeds relativistic radio jets and powers the
non-thermal emission (i.e., microquasars), whereas in others the power comes
from the wind of a young pulsar instead of accretion. Although the power
mechanism in these systems is different (accretion vs pulsar wind), all of them
are radio, X-ray and gamma-ray emitters, and have a high-mass bright companion
(O or B) star that is a source of seed photons for IC scattering and target
nuclei for hadronic interactions. I review here some of the main observational
results on the non-thermal emission from X-ray binaries as well as some of the
proposed scenarios to explain the production of gamma rays.
