In an attempt to observe the possible radioprotective actions of single or combined application of reduced glutathione(GSH) and cold exposure in mammals, the albino mouse was subjected to GSH injection, cold exposure at -1$pm$0.2C and whole-body X-irradiation with 900R either singularly or in combination, or the X-irradiation following the cold exposure and/or GSH injection. The level of protein of the liver, brain and heart was measured at one hour after each application, and the results were compared with the control, i. e., non-irradiated and non-cold exposed normal animal. Protein was measured by the method described by Lowry et al., using Folin-Ciocalteau phenol reagent. The results thus obtained are summarized as follows: 1) The level of protein in the liver, brain and heart of the normal mouse was 101.13, 62.75 and 87.08mg/gm wet wt., respectively. 2) The protein levels of all the organs studied were elevated by the X-irradiation, but decreased protein levels were observe when GSH was given. 3) In the group where the cold exposure was applied, and the X-irradiation was combined with the cold exposure, the protein levels of the organs were similar to the normal value or slightly deceased. 4) When GSH, X-irradiation and cold-exposure were combined, the protein levels of all the organs studied were decreased comparing with the normal.