Sampling of Polychaeta has been performed in the Persian Gulf and Gulf of Oman during December 2006 to October 2007. So far, 10 species belonging to six genera from two families have been identified. Seven species from the family Polynoidae (Lepidonotus natalensis, L. purpureus, Parahalosydnopsis arabica, Harmothoe hirsuta, H. liaoi, Paralepidonotus ampulliferous) and one species from the family Sigalionidae (Sthenelais boa) are new records for the Gulf of Oman. Thormora jukesii and H. marerubrum (Polynoidae) are new records for the Persian Gulf. Lepidonotus tenuisetosus could be recorded for both gulfs. The most diverse genera in the area are Lepidonotus and Harmothoe with each of them represented by three species. The most common species was Lepidonotus tenuisetosus, which was collected from 25 locations. The highest diversity of polychaetes species could be observed in rocky habitats containing stones covered with algae.