The article analyzes the activation of the use of prosimetrum in Kazakhstan Russian-language poetry of the second half of the twentieth century. We believe that this is due to, firstly, postmodernist search for new artistic forms, and secondly, the syllabic principle of versification typical of Kazakh poetry, in which poetry and prose are not clearly differentiated. Kazakhstan Russian speaking poets, using prosimetrum, organically combined Russian poetic traditions with Kazakh ones. The combination of prose and poetry within one poetic work became popular in the works of poets of the second half of the 20th century: Olzhas Suleimenov, Bakhytzhan Kanapyanov, Bakhyt Kairbekov, etc. Prosimetrum was used not only as a poetic device, as a way of searching for new expressive forms, but also contributed to the transformation of traditional genres, for example, the symbiosis of a parable and a dying song, a legend and a poetic aitys (“poets’ competition”), etc. As a result of syncretization, unique lyric-epic and lyrical genres of prose poetry appeared. The artistic and aesthetic potential of prosimetrum gave Kazakhstan poets the opportunity to realize postmodernist tendencies in expressing the real world and unstable reality, in creating a “text within a text”, in incorporating metaprose into a work, in complicating the subjective structure of an artistic text using the technique of self-reference, etc. In prose poetry, a prose fragment most often represents a metatextual commentary of the author, characterizing the poetic lines in terms of their source, origin, authorship, genre, and other parameters. Kazakhstan poets made full use of the “technical” possibilities of prosimetrum in creating a specific “uneven”, intermittent rhythm by alternating prose and poetic fragments. This rhythm became one of the specific features of the syncretic genre of prose poetry in Kazakhstan Russian-language poetry.