The paper presents results, including work in progress, related to study of Fragments from the Ladder of St. John of Sinai in the oldest Byzantine and Slavic Codices. The article published 10 fragments of the text of the Ladder as part of Simeon’s Miscellany according to the text of Izbornik of Svjatoslav 1073. The publication of the texts is based on the edition of the text of the Izbornik prepared by P. Janeva (Sofia, 2015) and is accompanied by indications of discrepancies in the most ancient Byzantine manuscripts of the Ladder and comments. The article contains clarifications and additions to the Sofia edition of the Izbornik. As a result of the study some fragments are reconstructed, I consider to be part of the lost Byzantine book, which became the source of the Bulgarian translation of the Simeon’s Miscellany. The article contains biblical quotations in the fragments of the Ladder as part of the Izbornik. The article lists the words of the Preslav literary school, typical for the translation of the Simeon’s Miscellany and for the first Slavic translation of the Ladder.