Józef Sulimowicz (1913–1973), a Polish Karaite, Turkologist and passionate bibliophile, collected a large number of Karaite manuscripts, books and documents in his lifetime. His collection, which includes items originating from both western communities and Crimea, is the only one of its kind in Poland. However, neither an inventory list, nor a catalogue have ever been assembled for the collection. Therefore, its exact content has remained largely unknown. The present paper discusses archival materials of the Karaite community in Lutsk stored in the Sulimowicz collection. It also looks at their origin, status and their research value.