Objective: The purpose of this study is to examine effects of work hardening program on grasp power, pinch power, and strength levels in work related hand injured workers. Materials and Methods: 26 workers with upper extremity work related injury, referred to our work hardening program. 19 were men and 7 were women and the average age was 36.6 years (range 25-63 years) The average elapsed time between onsst and participating in work hardening program was 277.5 days (range 89-1005 days). All participants underwent average of 4 weeks training. The grasp power, pinch power and strength levels were measured before and after training, Paired-t test was used to examine the difference of grasp power, pinch power and strength levels before and afterprogram. Subjective perception of the confidence of return to work was also measured by a simple questionaire after work hardening program. Results: All workers showed significant improvement in bilateral sides grasp power, pinch power and strength levels between before and after traning. All of the difference of bilateral sides grasp power, pinch power and strength levels before and after work hardening are all statistically significant (p＜.001). 85% trainees agreed that their confidence level of return to work had improved after participating in this program. Conclusions: Work hardening program in this study improve grasp power, pinch power and strength levels of injured workers. The physical capacity fulfilled the work demand after traing therefor their confidence of return to work increased.