The article discusses documents in Portuguese Aljamía (Portuguese texts in the Arabic alphabet script). Unlike Spanish Aljamiado, the common basis for an extensive literature, including fiction, only eight manuscripts are known to have been written in Portuguese Aljamía. Six of them are letters to the King of Portugal from his subjects in Morocco that report the military and political situation in the Portuguese colony. Portuguese Professor David Lopes first published these manuscripts in 1987, with detailed comments not only on the history of Portuguese-Arabic documents, but also on their spelling. Spanish language texts in Aljamiado transcription are significantly different from those in Portuguese, although there are some common features. As is the case with Arabic texts, in the texts under analysis, initial syllables cannot have two consonants or two vowels in a row, which creates certain difficulties in the transcription of diphthongs. The Spanish Aljamiado text vocalization is also more developed than the Portuguese Aljamía text. All Portuguese Aljamía letters contain greeting clichés from the Arabic language changed when translating: “Nome de Deus misericordioso”, “Louvores ao seu Deus”. In one letter there is a rare phonetic inscription of the Arabic word: “God” () instead of etymological, adopted in the Spanish Aljamiado’s texts of the corresponding period. The Turk’s oath that mentions the attributes of all three Abrahamic religions is of particular interest. The letters can be identified not in terms of nationality, but religion.