Magneto‐optical spectroscopy and hysteresis loops have been used to studynondestructivelythe effect of 100‐keV Ne+implantation in epitaxial Y3Fe5O12thin films. The results show the formation of a damaged layer of 0.13 &mgr;m thickness. The stress‐induced anisotropy field reaches maximum values of 3.2×104A/m for an ion dose of 2×1014cm−2. A decrease in both magnetization and magnetostriction down to 3.6×104A/m and −1.2×10−6, respectively, was observed for an ion dose of 4×1014cm−2. The magneto‐optical spectra were found to reduce in magnitude but not in shape with increasing implantation dose.