The article deals with the history of competition and standardization between the variants од‑/ від‑ (both as preposition and prefix) in the Ukrainian language. Historically they are related to different groups of dialects. In the southwestern dialectal zone, with the exception of the northern dialects of the Volyn and Carpathian areas, the variant від‑ prevails, while the variant од‑ is predominant in the north of the country. The variant од‑ was typical for standard Ukrainian of the 19th‑early 20th century. After a period of competition with від‑ it lost out because of the artificial limitation of its use. This happened in the early 20th century due to the desire to employ forms that would give the literary language a national character, since the від‑ variant is notably different from both Polish and Russian. The history of од‑/ від‑ competition is investigated on the material of dictionaries, 1920s’ grammars and modern linguistic research. The history of од‑/ від‑ preposition and prefix variants was researched as well within the Ukrainian language corpus, which includes texts from the 19th to the 21st centuries. Shown are the points of variation related to regional and chronological properties, to authors’ individual preferences and to certain lexemes.