From 1956–1961 Bilash worked as an Instructor of music theory at the Kyiv Pedagogical Institute (Kyiv Teachers Training Institute, now Borys Grinchenko Kyiv University). Already Bilash had emerged as a pre-eminent and prolific Ukrainian composer who had contributed immensely to variety of musical genres and styles. Many of his lyric songs became very popular in Ukraine. His lyric songs have become a part of the 'golden fund' of Ukrainian national culture and many of them are often perceived as traditional folk songs. He composed the opera "Haydamaky" (1965), "The Ballad of War" (1971), "The Grooms" (1985), operetta "The Legend of Kyiv", "The Bells of Russia". Bilash opposed the soundtrack to numerous movies. One of them - "Roman and Francesca" (1960) with the celebrated lyric songs by Bilash was the first Soviet film (musical) where love between a Soviet sailor and a foreign girl was not criminalized. At the time of Chernobyl nuclear accident in April 1986, the popular lyric song "Dva kolyory" (Two colors) composed by Oleksandr Bilash sounded like a revelation.