Аннотация:We report the very first detection of γ-ray resonant absorption along the line of sight toward γ-ray bright quasars (QSOs), like 3C273, 3C279, PKS0528+0134 and BL Lacertae. These detections resulted from the analysis of COMPTEL and EGRET data that were collected during monitoring campaigns of the Virgo and galactic anticenter regions by the Compton Gamma Ray Observatory (CGRO), or during ToO observations of QSOs flares. At least two absorbers are detected on the sight lines towards γ-ray bright QSOs, one at the QSO rest frame redshift, and another at the redshift that has an ~0 value. The latter we tentatively identify with the absorber in the galactic halo, while the former is undoubtedly caused by the photon absorption in the host galaxy of the QSO.