  We present a detailed study of the effects of gravitational microlensing on
compact and distant $\gamma$-ray blazars. These objects have $\gamma$-ray
emitting regions which are small enough as to be affected by microlensing
effects produced by stars lying in intermediate galaxies. We analyze the
temporal evolution of the gamma-ray magnification for sources moving in a
caustic pattern field, where the combined effects of thousands of stars are
taken into account using a numerical technique. We propose that some of the
unidentified $\gamma$-ray sources (particularly some of those lying at high
galactic latitude whose gamma-ray statistical properties are very similar to
detected $\gamma$-ray blazars) are indeed the result of gravitational lensing
magnification of background undetected Active Galactic Nuclei (AGNs).
