Long term BeppoSAX-WFC monitoring of GRS 1758-258

Following a series of deep observations of the Galactic Bulge region performed with the Wide Field Cameras on board BeppoSAX, it has been possible 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 characteristics. The source has been monitored for almost 2 years since August 1996; preliminary results of the data analysis are shown hereafter.