The present study deals with the diversity of the genus Paradoneis (Annelida: Paraonidae) from the Sea of Marmara. Examination of materials collected from various soft and hard substrata from depths between 10 and 1200 m in the region revealed the presence of four species, among which one was already known from the region (P. ilvana), one was a new record for the Sea of Marmara (P. armata) and other two (P. heterochaeta n. sp. and P. longifurcata n. sp.) were new to science. Paradoneis heterochaeta n. sp. is characterized mainly by having a proportionately large size, by its pigmentation on the body, by bearing minute notopodial postchaetal lobes and by possessing two types of lyrate chaetae. Paradoneis longifurcata n. sp. is mainly characterized by having weakly jointed notopodial postchaetal lobes and lyrate chaetae with the long branch being up to 4.5 times longer than the short branch. All species found in the area are described and discussed.