The WeeFIM is an outcome measure used worldwide to evaluate the functional abilities of children. The aim of this study was to evaluate the psychometric properties of WeeFIM in Korean children with cerebral palsy (CP) using the Rasch model. The mean age of the participants (92 boys and 53 girls) was 10.6 years (SD=2.3, range 5~15 years). The Winsteps software was used for analyzing the internal construct validity and reliability of WeeFIM. For analyzing the internal validity the motor and cognitive area items of the WeeFIM were analyzed both together and separately. When all 18 items were analyzed 4 were considered to be misfits; upper extremity dressing, lower extremity dressing, toileting, and comprehension. When only the 13 motor items were analyzed, toileting, bladder management, and bowel management were considered misfits. In addition, only comprehension was considered as a misfit among the 5 cognitive items. The most difficult motor items were stair climbing, and bathing. The simple ones were eating, bowel management, and bladder management. The most difficult cognitive item was problem solving, and the simplest one was comprehension. The person separation indexes and reliability for combined and divided instruments were reported as excellent. These results demonstrated the applicability of WeeFIM to Korean CP children with satisfactory reliability and validity. Further studies should include young children with CP and compare item difficulty among the different types of CP. In addition, the Korean normative data of nondisabled children should be used to compare the cultural differences between Korea and other countries.