The purpose of this study was to investigate the effect of mental practice on the upper extremity function of the hemiplegic Patients, 8 subjects with hemiplegia patients participated in this study. They did the Mental Practice programme for twenty minute, two times a week, three weeks. The Mental practice effects was evaluated by Fugl-Meyer Assessment(FMA), Action Research Arm Test(ARA), Stroke Rehabilitation Assessment of Movement(STREAM). The data were analyzed using paired t-test. The result of this study are as follows: FMA score were significant difference test-retest(p<.05), ARA score were statistically significant improvement between test-retest(p<.05), On the STREAM, the patients had the score improved on 4 of the 10 items of the upper-extremity Scale. The result suggest that mental practice is a potentially useful method of practicing motor skills. Mental practice may be a cost-effective, non-invasive tool with wuhich patients with stroke can receive additional practice of functional skills, and realize greater outcome, than if therapy alone were used.