The library of St Catherine's Monastery in Sinai holds a remarkable series of documents issued over several centuries by the authorities of Fatimid, Ayyubid, Mamluk and Ottoman Egypt to guarantee the protection of the monks. The decrees issued at the highest level, for example by the Mamluk sultans, have been studied. This present study concentrates on eighteen documents of the Mamluk period, not before edited, which were issued by officials of lower rank. After an introduction, which briefly presents the monastery, its archive and general comments on the diplomatic of the documents, the text of each is established and translated into English with a commentary. The form and style of the documents are compared to those of relevant examples found in the scribal handbooks, including an unpublished work by the son of al-Qalqashandi. These documents not only reinforce the general aims of the sultanian decrees but also deal with some specific issues, the security of the monks and their ability to carry on commercial activity, and demonstrate a secondary level of administration that gave effect to orders from the centre. The original texts are fully reproduced.