The Leningrad Codex is one of the oldest known manuscripts of the complete Hebrew Bible produced according to the Tiberian masorah (“transmission”); according to its colophon it was produced in 1008. The Aleppo Codex is the only known older such manuscript; the Aleppo was completed several decades earlier and was used as the proof-copy against which the Lenigrad Codex was corrected. However, major parts of the Aleppo Codex have been missing since 1947; thus the Leningrad Codex is the oldest intact codex of the Tiberian masorah. The former owner of the Codex, the Karaite collector Abraham Firkovich, never stated where he had acquired it. It was taken to Odessa, Russia in 1838 and was later transferred to the Imperial Library in St. Petersburg. The Codex is now housed there in the National Library of Russia.

According to its colophon, the codex was produced in Cairo from manuscripts written by Aaron ben Moses ben Asher. Some scholars believe that it is a product of the ben Asher school itself; however, no evidence exists that ben Asher ever saw it. The most notable feature of the Leningrad Codex is the source of most of its orthography: unusually for a Masoretic work, the consonants, the vowels, and the Masoretic notes were all written by the same person, Samuel ben Jacob. The Leningrad Codex, and the Aleppo Codex which was edited by ben Asher himself, appear to be the most faithful to ben Asher’s Masoretic tradition of any other surviving texts from later periods that are not based upon these two codices. Since the Leningrad Codex contains numerous corrections, alterations, and erasures, it has been postulated that the Leningrad Codex was an existing text that did not follow ben Asher’s rules and was altered into conformance.

The order of the books in the Leningrad Codex follows the Tiberian textual tradition, which is followed by the later tradition of Sephardic biblical manuscripts; however, there are significant differences in the order of its books in Ketuvim (Writings)—the order in the Codex is: Chronicles, Psalms, Job, Proverbs, Ruth, Song of Songs, Ecclesiastes, Lamentations, Esther, Daniel, Ezra, Nehemiah. In recent times, the Leningrad Codex was used as the source of the Hebrew text reproduced in Biblia Hebraica (1937) and Biblia Hebraica Stuttgartensia (1977). It also is used by scholars as a primary source for the recovery of details in the missing parts of the Aleppo Codex.