In order to evaluate the effects or the effectiveness of applying isokinetic exercise in addition to routine rehabilitation treatment for hemiparesis for the improvement of muscle strength and function a n d in the motivation for recovery achievement,a n experimental study was conducted with 20 hemiparesis hospitalized or receiving ambulatory care after discharge. 10 were randomly assigned to the control group receiving routine rehabilitation treatment plus isotonic exercise, and another 10 patients to the exercise group treated with isokinetic exercise using a Rehabilitation and Testing System(Model Cybex350), in addition to routine rehabilitation treatment for six weeks. The following results were obtained: 1. The gait speeds for 20m walking significantly increased in the exercise group after 6 weeks treatment as compared measured at iliopsoas and gluteus maximus muscles increased more in both involved and uninvolved muscles of the exercise group than of the control group, without showing statistically significant differences. 3 . The peak torques and the ratios of peak torque to body weight continuously increased during the treatment period of 6 weeks, and significantly increased in the exercise group as compared to the control group after 6 weeks(p<.0.05). 4. Measurement of iliopsoas muscle(p<0.05), and also at 30° /sec and 60° /sec in gluteus Maximus muscle(p<0.05) for the exercise group as compared to the controls. 5. Average power improved to a great extent after 6 weeks, and the exercise group showed more significant increases at 60° /sec and 90° /sec in involved iliopsoas muscle and at 60° /sec in involved gluteus maximus muscle than the control group(p<0.05). 6. The changes in torque acceleration energy did not show significant difference between two groups after 6 weeks, and, however, there were more increases overall in the exercise group than in the controls.