Long term BeppoSAX-WFC monitoring of GRS 1758-258

Following a series of deep observations of the Galactic Bulge region perfor med with the Wide Field Cameras telescopes on board BeppoSAX, it has been p ossible to study throughout a long time period a number of persistent X-ray sources. We report on the behaviour of GRS 1758-258, an X-ray binary suggested as a black hole candidate on the basis of its timing and spectral characteristic s. The source has been monitored for almost 2 years since August 1996; prel iminary results of the data analysis are shown hereafter.