The aims of this study were to apply for the first time the Action Research Arm Test for functional assessment of an allotransplanted upper extremity (hand or forearm), to describe any adaptations required to this test system for the abovementioned purpose, and to use this test to record any changes in outcome over time. A structured approach to the Action Research Arm Test was adopted including interrater and intrarater reliability assessment at the very beginning of its use and ongoing comprehensive monitoring of patients through regular checkups. Four male patients who had undergone hand or forearm allotransplantations, in the authors' center, were examined. All 19 items in the Action Research Arm Test were reviewed, and the total score was calculated, taking into account the given time limits for each item. All patients showed a marked clinical improvement in their test results over time. They continued to have difficulties with performing items in the pinch subtest. The intrarater and interrater assessment achieved consistent results. The data of this study indicate that the Action Research Arm Test is suitable for assessing the level of upper extremity function. The test can be used to compare functional outcomes after hand and forearm allotransplantation between different centers, providing objective information concerning the quality of reconstruction.