The purpose of this study was to determine the effect of releasing of immobilization on glycogen metabolism of hindlimb muscle after 7days use of a hindlimb casting in mice. The experimental group was divided into control group and recovery groups after removal of left hindlimb casting. The recovery groups, were subivided into the 0, 3rd and 5th day after removal of left hindlimb casting. The results were as follows; 1. The degree of atrophy of hindlimb muscles by 7 days immobilization was measured by ratio of muscle to body weight in plantaris and soleus muscles. The muscle to body weight ratios of plantaris and soleus muscles were decreased by 88% and 74%, respectively on the day of cast removal. The ratios of the both muscles were increased to the level of the control values on the 3rd and 5th day removal of casting. 2. A significant reduction of the glycogen concentration in gastrocnemius muscle occurred after 7 days hindlimb immobilization. The glycogen concentration in gastrocnemius muscle was decreased by 63% on the day of cast removal. The glycogen concentration was recovered to the values of the control group on the 3rd and 5th day after removal of hindlimb casting. 3. The level of muscle glycogen concentration of 25% glucose ingested control group was almost twice that of the normal diet control group. The muscle glycogen concentration of glucose ingested group was significantly less by 81% after 7 days of immobilization compared with the respective control gmup. The concentration recovered to the values of control on the 3rd and 5th day after removal of hindlimb casting. In contrast, there was no significant difference in the liver glycogen concentration between the immobilized grop and the cast removed group in which was removed. 4. The effects of releasing of hindlimb immobilization on plasma glucose, insulin concentration and insulin - glucose ratio were not significant difference statistically, but possibly related with recovery of glucose metabolism in atrophied muscles. In summary, the deteriorated glycogen metabolism of skeletal muscle which occurred in the short period hypokinesia or akinesia can be recovered rapidly by removal of the factors of hypokinesia and akinesia.