The purpose of this study was to identify the effect of cerebral ischemia on affected(Lt) and unaffected(Rt) side of soleus, plantaris and gastrocnemius muscle mass and determine the effect of exercise on affected and unaffected side of soleus, plantaris and gastrocnemius muscle mass during acute stage of stroke. Sixteen male Sprague-Dawley rats with 200-270g body weight were randomly divided into three groups: control, stroke, and exercise after stroke(St+Ex) group. The control group received sham operation and the stroke group and St+Ex group received transient right MCA(middle cerebral artery) occlusion operation. The St+Ex groups ran on a treadmill for 20min/day at 10m/min and 10° grade for 6days. During the experimental period body weight and diet intake was measured every morning. On the 7th day after operation, muscles were dissected from both affected and unaffected side of hindlimb. Cerebral infarction of stroke and St+Ex groups were identified by staining with TCC for 30minutes. The data were analyzed by Kruskal-Wallis test and Mann-Whitney U test using the SPSSWIN 9.0 program. Significance was accepted at the level of p<0.05. The results were summarized as follows : 1) There were no significant difference of the body weight on the firsrt day of experiment among 3 groups. Whereas on the 7th day, the body weight of both stroke group and St+Ex group were significantly smaller than that of control group. Body weight of St+Ex group on the 7th day tended to be larger than that of stroke group. 2) Total diet intake of both stroke group and St+Ex group were also significantly smaller than that of control group. While total amount of diet intake in St+Ex group tended to be larger than that of stroke group. 3) The weight of gastrocnemius muscle of affected side in stroke group significantly decreased compared to that of control group and the weight of soleus and plantaris muscle of affected side in stroke group tended to decrease compared to that of control group. 4) The weight of plantaris muscle of unaffected side in stroke group significantly decreased compared to that of control group and the weight of soleus and gastrocnemius muscle of unaffected side in stroke group tended to decrease compared to those of control group. 5) The weight of gastrocnemius muscle of affected side in stroke group significantly decreased compared to that of unaffected side and there was no significant difference of the weight of soleus and plantaris muscle in stroke group between affected side and unaffected side. 6) The weight of soleus, plantaris and gastrocnemius muscle of both affected side and unaffected side in St+Ex group had a tendency of increase compared to those of stroke group. The relative weight of soleus and gastrocnemius muscle of affected side and soleus muscle of unaffected side in St+Ex group had a tendency to increase compared to those of stroke group. Based on these results, exercise during acute stage of stroke might attenuate muscle atrophy of both affected and unaffected side of hindlimb muscles.