The Ostrog Bible (Ukrainian: Острозька Біблія, translit. Ostroz’ka Bibliya; Russian: Острожская Библия, translit. Ostrozhskaya Bibliya) was one of the earliest East Slavic translations of the Bible and the first complete printed edition of the Bible in Old Church Slavonic, published in Ostroh, in the Polish-Lithuanian Commonwealth (modern territory of Ukraine), by the printer Ivan Fyodorov in 1581 with the assistance of the Ruthenian Prince Konstantin Ostrogski.
The Ostrog Bible was translated not from the (Hebrew) Masoretic text, but from the (Greek) Septuagint. This translation comprised seventy-six books of the Old and New Testaments and a manuscript of the Codex Alexandrinus. Some parts were based on Francysk Skaryna's translations.
The Ostrog Bibles were printed on two dates: 12 July 1580, and 12 August 1581. The second version differs from the 1580 original in composition, ornamentation, and correction of misprints. In the printing of the Bible delays occurred, as it was necessary to remove mistakes, to search for correct textual resolutions of questions, and to produce a correct translation. The editing of the Bible detained printing. In the meantime, Fyodorov and his company printed other biblical books. The first were those that did not require correcting: the Psalter and the New Testament.