The present study deals with the first occurrence of Prionospio (Prionospio) paucipinnulata in the Mediterranean Sea. It was collected on muddy bottom at depths ranging from 4.5 to 35 m on the Aegean (Gokova Bay) and Levantine coasts of Turkey (Iskenderun Bay) in 2000 and 2009. This species is mainly characterized by a long caruncle and the arrangement of apinnate (second and fourth) and pinnate (first and third) branchiae through the body, which have a few number of pinnules. This species could have been introduced to the Mediterranean from the Pacific Ocean (southern Australia) via ballast water of ships. The morphology, ecology and distribution of the species are explained.