The technique used to reveal palimpsest texts of the Library of St. Catherine’s Monastery at Mount Sinai has succeeded in the discovery of Christo-Palestinian Aramaic texts from the most ancient witnesses of this literature, possibly from the 6th century AD. Manuscript Sin. syr. NF M56N (CPA), consisting of 114 folios, is particularly remarkable. This manuscript reveals a great deal of codicological information. It reused 45 folios of an ancient Christian Palestinian Aramaic codex which can be reconstructed with great precision. Quires are quaternions, with the fleshside outside with ‘en miroir’ signatures. The layout is regular: two columns of 23 lines; system of ruling and pricking; decoration is used: big crosses inscribed in circles as drop caps mark the beginning of pericopes; the initials for many sentences are coloured and ornamented; calligraphy is beautifully realised; punctuation is regular. Moreover, this manuscript is a precious witness for two New Testament texts translated from Greek into Christian Palestinian Aramaic. Extensive passages are legible, some of which had been previously unknown in this language. The codex was a Gospel book containing Matthew and Mark. A critical edition is in progress. Already at this point, it seems clear that the text is a good representative of what I have called ‘the Christo-Palestinian Vulgata’ that was in use among Chalcedonian Christians of Palestine and Arabia as early as the 6th century. One can note also the presence of a system of synoptical references in the margins. Moreover, each Gospel text includes subtitles with numbering.