AbstractWe present the scientific goals and the strategy of the REX survey, a project which has been recently initiated at the Brera Astronomical Observatory in Milan with the aim of selecting a large and statistically representative sample of BL Lac objects and other kinds of Radio Loud Active Galactic Nuclei. More than 1200 PSPC images (for a total of about 2700 square deg. of sky) have been searched for sources detected also in the VLA NVSS survey (as of June 1977). The data and source selection criteria, the cross‐correlation technique and preliminary results are presented and discusse