Darfur (Sudan) is characterized by significant linguistic diversity (Nilo-Saharan, Niger-Congo and Afro-Asiatic languages). However, many languages and dialects in the five states of this Sudanese region are endangered or already extinct. The sphere of oral communication is dominated by the Sudanese Arabic dialect. In the realm of writing and literacy, only literary Arabic is officially recognized, although for several centuries there has been an “invisible” written tradition in the Sudanese dialect. The article discusses practically all the known cases when the use of the Fur language in Arabic script (Ajami) was attested by Sudanese and foreign scholars. It is noted that the local variety of Ajami in the Fur language in Darfur apparently has never become widespread, unlike the different forms of Ajami in Borno, despite the historical ties between these two regions. The Fur Ajami has remained “invisible”, while literary Arabic has dominated the field of written communication. The article also tackles a number of modern attempts to adapt Arabic or Roman script to the Fur language (in Sudan and in the Darfurian diaspora abroad).