120 mice of both sexes weighing from 18 to 22 g. were used. These mice were divided nito 12 groups : control (non-restraint and restraint) , acclinmation (non-restraint and restraint , acclimation for 5 and 10 days) , adrenalectomized (non-restraint and restraint0 and acclimation-adrenalectomized (non-restraint and restraint, acclimation for 5 and 10 days) groups. The rectal temperature of each group were measured at 10, 30 and 50 min under environment of $0^{circ}C$.Measurements were done with a microphrometer of B.T.-32 thermocorpules. The results obtained may be summarized as follows : 1) The rectal temperature in normal mice without restraint was higher than that of normal mice with restraint under environment of $0^{circ}C$. 2) The rectal temperature in normal mice was higher than that of adrenalectomized mice at 20$^{circ}$ C. But the rectal temperature in adrenalectomized mice without restraint was higher than that of adrenalectomized mice with restraint under cold-stress. This difference was in the order of 1.65$^{circ}$ under environment of 20$^{circ}$ and 10 $^{circ}$ at 50 min under environment of 0$^{circ}$. 3) The rectal temperature of normal mice with restraint was less than that of adrenalectomized mice (non-restraint) under cold-stress. 4) The rectal temperature of normal and adrenalectomized mice that acclimated under cold stress ($0^{circ}C$) for 5 and 10 days was usually higher than that of normal and adrenalectomized mice of non-acclimation under environment of $0^{circ}C$. 5) The tolerance in mice under cold-stress was increased on the acclimtion of cold.