The article examines the process of the influence of barbarization on the fighting condition of the late Roman army in the period of the IV century A.D. The relevance of the study is the debatable question of the nature of the influence of barbarization on the problem of the fighting condition and effectiveness of the late Roman troops. The purpose of the study is to analyze the combat state of the Roman army of Late antiquity, which developed at the time of the 4th century AD and to study the reasons that caused the Roman rulers to attract a wide contingent of barbarians to the legions. The work is based mainly on the analysis and synthesis of the content of written sources by late Roman authors, covering data on the combat condition of the legions of the IV century AD. As a result of the study, the authors came to the conclusion that the combat condition of the Roman army in the period of the IV century A.D., in conditions of a wide predominance of the barbarian element, did not lead to significant problems and weakening of the combat condition, but rather was a response to existing problems within the Roman state, striving to preserve combat potential. The content of the information from the article may be applicable to scientists dealing with the problem of the military art of the Roman army of the Dominant era.