Background: The presence of visuospatial impairment can make patients slow functional recovery and impede the rehabilitation process in TBI patients. Objective: The aim of this study is to investigate effects of prism adaptation treatment for functional outcomes in patients following traumatic brain injury. Methods: The subject received prism adaptation treatment for 2 weeks additionally during traditional rehabilitation for 4 weeks. The Patient has prism adaptation treatment while wearing wedge prisms that shift the external environment about 12° leftward. The patient received 10 sessions, 15-20min each session. Outcome measures were visuospatial deficit(line bisection, latter cancellation), Visual and spatial perception(LOTCA-visual perception and spatial perception), motor function of upper extremity(FMA U/E; Fugl-Meyer motor assessment upper extremity, ARAT; Action research arm test), balance(BBS; Berg Balance Scale), mobility(FAC; Functional ambulation classification) and functional level(FIM; Functional independent measure). All Assessments took place on study entry and post-treatment assessments were performed at discharge from the hospital. Results: After prism adaptation, the visuospatial impairment scores improved as indicated in the line bisection(-15.2 to -6.02), latter cancellation(2 to 0) and LOTCA- spatial perception scores(7 to 9). The upper motor function improved as indicated in the scores of affected FMA U/E(21 to 40) and ARAT(4 to 22). Ambulation and balance improved as indicated in the BBS scores(25 to 38) and FAC scores(0 to 4). ADL function improved as indicated in the FIM total scores 54 to 70(motor 34 to 61, cognition 20 to 29). Conclusion: Prism adaptation did improve functional level such as motor functions and ADL abilities in TBI patient. Further research is recommended.