Most counterparts of the identified low-latitude gamma -ray sources are isolated neutron stars (INSs). Since INSs are characterized by an extremely high value of f sub(X)/f sub(opt), a systematic X-ray/optical coverage of the fields of unidentified low-latitude gamma -ray sources is the best way to unveil INS counterparts of unidentified sources. Since the low-latitude sources are heavily affected by the interstellar absorption in both the X-ray and optical bands, we decided to apply the above strategy to two middle-latitude EGRET sources, which could belong to a local galactic population: 3EG J0616-3310 and 3EG J1249-8330. Here we report on the global X-ray characterization of about 300 objects, on their candidate optical counterparts and on the preliminary results of their identification.