Studies were conducted to determine the concentration of anionic surfactants in selected waters in Tricity agglomeration (Gdańsk, Gdynia, Sopot). Water samples were taken from November 2001 to May 2002. The total concentration of anionic surfactants in the environmental samples was determined by Methylene Blue Active Substances Method (MBAS). The concentration of anionic surfactants in the analyzed waters ranged from 5 to 150 ^g/dm3. The highest surfactant content was observed in the Strzyża stream in Gdańsk and the Kacza river in Gdynia. Less polluted were the Haffner stream in Sopot and the Oliwski stream in Gdańsk.