Objective : This study was conducted to assess the changes in the functional levels of affected upper extremities after treating patients with brain injury by intensive CIMT (Constraint-Induced Movement Therapy). Method : Design was single-subject experimental reversal design (A-B-A). Subjects was 6 persons with brain injury (F: 1, M: 5), mean age (57.0±9.6). Intensive CIMT was performed over 6 hours a day for 2 weeks. Box and block test and nine hole pegboard were used for assessment of affected upper extremity function before and after intervention. Results : Compared baseline 1, functional level in both intervention and baseline 2 revealed improved functional levels. In addition, carry over effect was shown in baseline 2 period. Conclusion : Intensive CIMT based on task-oriented activity is considered to be effective because it decrease the time to use the paretic limb and thereby overcomes the “learned nonuse”.