The article is devoted to the research of the process of accentual change in the group of Ukrainian adjectival verbs on '-iti' of the type 'zbilshiti, polegshiti, primenshiti, rozmyakshiti', etc. It is established that the original stress for them was the stress on the last syllable, as e.g.: zbilszi'ti -zbilshu', zbilshi'sh, etc. In the author's opinion these transformations were caused by the development of the verbal aspect category and subsequent change of the aspectual correlative pairs. The process of word formation is seen here to change the imperfective aspect with stressed suffix -a- of the type zbilsha'ti, zbilsha'yu, zbilsha'esh by the root stressed word forms of the imperfective aspect on '-uva-' of the zbi'lshuvati - zbi'lshuyu, zbi'lshuesh type. In this way, the original aspectual relation zbilsha'ti -zbilshi'ti was changed into a new one: zbi'lshuvati - zbi'lshiti.