  Since its launch on October 2002 the INTEGRAL satellite is performing an deep
survey of the hard X-ray sky with unprecedented sensitivity and positional
accuracy. This allowed pinpointing, through positional cross-correlation with
catalogs at longer wavelengths, possible optical/near-infrared candidates for
the hard X-ray sources of still unknown nature. In this presentation I will
describe this work as well as the observational activities aimed at
determining, through optical spectroscopy, the nature of the unknown INTEGRAL
sources, along with the main results of this search. Future prospects about
this identification program will also be illustrated.
