The effects of γ-irradiation on mid-IR transmitting glass have been investigated using bulk samples of nominal composition 0.575 ZrF4-0.0875 ThF4-0.3375 BaF2. A 1 krad dose caused a marked increase in losses in the UV and visible regions. However, no recordable change was produced by a 45 Mrad dose in the wavelength range 2.5 to 4 μm.