  LS 5039/RX J1826.2-1450 is one of the few High Mass X-ray binary systems from
which radio and high energy TeV emission has been observed. Moreover,
variability of the TeV emission with orbital period was detected.
  We investigate the hard X-ray (25 - 200keV) spectral and timing properties of
the source with the monitoring IBIS/ISGRI instrument on-board the INTEGRAL
satellite.
  We present the analysis of INTEGRAL observations for a total of about 3 Msec
exposure time, including both public data and data from the Key Programme. We
search for flux and spectral variability related to the orbital phase.
  The source is observed to emit from 25 up to 200 keV and the emission is
concentrated around inferior conjunction. Orbital variability in the hard X-ray
band is detected and established to be in phase with the orbitally modulated
TeV emission observed with H.E.S.S. For this energy range we determine an
average flux for the inferior conjunction phase interval of $(3.54 \pm 2.30)
\times 10^{-11}$ erg cm$^{-2}$ s$^{-1}$, and a flux upper limit for the
superior conjunction phase interval of $1.45 \times 10^{-11}$ erg cm$^{-2}$
s$^{-1}$ (90% conf. level respectively). The spectrum for the inferior
conjunction phase interval follows a power law with an index $\Gamma =
2.0^{+0.2}_{-0.2} $ (90% conf. level).
