Abstract Background. One of the most important problems of modern Ukrainian linguistic studies is the comprehensive study of the language as a dynamic system, which has recently been noticeably «updated» at all levels. Under the influence of a number of social factors the lexical-semantic and derivational systems change most noticeably, the dynamics of other linguistic systems, morphological system in particular. In various socio-communicative fields, the functioning of many variabilities of grammatical forms of verbs that show the category of aspect of the verb is observed. New tendencies in the formation of perfectives and imperfectives in this regard are the most significant, they are most active in informational and publicistic, scientific, literary discourses. The purpose of the article is to identify and prove specific features of perfectivations / imperfectivation of aspectual pairs of verbs in the language of prose of P. Zahrebelnyi The main tasks of the article: to describe the writer's perfectives and imperfectives as stylisthemes that in the literary discourse of the prose writer represent the category of occasionality; specify the methods of their derivation; identify the main functions of stylisthemes in the author's novel. Methods. In this publication were used general scientific methods such as observation, analysis, synthesis and comparison; within linguistic methods, there is the descriptive method which is used for interpretation of perfectivation / imperfectivation in the literary discourse of P. Zagrebelny; method of integrative analysis is the basis of the overall study of the set of stylistic matters that represent the grammatical category of aspect in the writer’s language; method of linguistic analysis allows to determine stylistic functions of author’s individual perfectives and imperfectives in the vertical context of analyzed novels. Results. In the morphological system of the modern Ukrainian literary language, not all verbs form aspectual pairs. One-aspect (non-biaspectual) verbs form quite a steady subsystem within the verbal system of the Ukrainian language. However, within grammatical verb categories span different points of tense, aspect, state, the person of a verb, functioning of active and passive particles became visibly active from the end of the 80s – beginning of the 90s of XX century. At the beginning of the 20s of the XXI century we can see consequences of tendencies that not only show the dynamic nature of the verbal system but also the dynamic consistency of grammatical norms. In the language of P. Zagrebelny's fiction, potential verbs, identifying the category of occasionality, reflect modern tendencies in the development of the Ukrainian language and can strengthen the potential of the literary standard. In the works of the author, written in the 60’s – the early ‘80s of last century, grammatical forms are found, which represent the perfection of verbs of imperfect form and the imperfection of verbs of perfect form, which in modern Ukrainian became more active only in the late 80’s – early ‘90s of the twentieth century. A specific feature of the writer’s linguistic style is the active production of aspectual pairs, which in the vertical context of his language creative work acts as a stylistheme. The whole set of individual author's perfectives and imperfectives is a consequence of an unusual (previously untraceable) combination of usual morphemes. Discussion. Numerous potential verb forms that mark the literary discourse of P. Zahrebelnyi demonstrate the author's linguistic sense to choose the ways of development of the Ukrainian language, the knowledge of tendencies of activation of its grammatical phenomena during the last few decades in particular. From the '60s of the twentieth century, the writer actualized numerous forms within verb grammatical categories, in particular the verb category of the form, which mostly corresponds to the modern linguistic and literary standard, significantly diversified the language of fiction with stylisthemes that are potentially close to commonly used linguistic units. We see prospects for further research of this topical problem in a comprehensive study of individual author's formation within the verb categories of state and personality / impersonality, which also reflect the dynamics of the stylistic norm of the modern Ukrainian literary language, represented in literary discourse. Keywords: grammatical category of aspect, perfective, imperfective, stylistic norm, literary discourse.