In order to determine the tintinnid species and abundance in the Gulf of Gemlik and some ecological variables that affect the distribution of the species, samples were collected with a Ruttner bottle and a plankton net (40 mu m) at 11 stations (6 shore, 5 offshore) between in June 2010 and May 2011 monthly. The examination of the samples, 28 tintirmid species belong to 7 familia, 12 genera were identified. According to the literature information, 18 species were new entries for the Marmara Sea, and 4 of them were also new entries for the Turkish coastal waters (Eutintinnus medius (Kofoid and Campbell) Kofoid and Campbell, 1939, Metacylis mediterranea (Mereschkowsky) Jorgensen, 1924, Tintinnopsis acuminata Daday, 1887 and Tintinnopsis urnula Meunier, 1910). The majority of the species composition was represented with Codonellidae and Tintinnidae families (both of them had 8 species, 28.6 %). The genus Tintinnopsis were observed as dominant when compare with the others according to numbers of individuals. Primary hydrographic conditions such as temperature (8.1-29.3 degrees C), salinity (14.98-38.65 ppt), dissolved oxygen (2.06-17.18 mg l(-1)), and pH (7.7-8.8) were recorded maximum and minimum values at each sampling station.