  A new type of high-energy binary systems has been revealed by the INTEGRAL
satellite. These sources are in the course of being unveiled by means of
multi-wavelength optical, near- and mid-infrared observations. Among these
sources, two distinct classes are appearing: the first one is constituted of
intrinsically obscured high-energy sources, of which IGR J16318-4848 seems to
be the most extreme example. The second one is populated by the so-called
supergiant fast X-ray transients, with IGR J17544-2619 being the archetype. We
report here on multi-wavelength optical to mid-infrared observations of a
sample of 21 INTEGRAL sources. We show that in the case of the obscured sources
our observations suggest the presence of absorbing material (dust and/or cold
gas) enshrouding the whole binary system. We finally discuss the nature of
these two different types of sources, in the context of high energy binary
systems.
