Mono- and dimethylphenanthrenes were determined in recent (0-10 cm) sedimentscollected at about 30 stations in the southern Baltic Sea from 1995 to 2001.The stations were located in the Szczecin Lagoon, the Pomeranian Bay, theBornholm Deep, the open sea (without the Bornholm and Gdańsk Deeps), theGdańsk Deep, and the Gulf of Gdańsk including the Wisła (Vistula) Lagoon.The results were related to the unsubstituted PAH content. The annual load ofmethylphenanthrenes in relation to unsubstituted PAHs in the Rivers Odra andWisła was estimated. Methylphenanthrenes are more abundant in the Odraestuary than in the Wisła estuary, and more abundant in the coastal sedimentsthan in the open sea sediments. The results indicate that methylphenanthrenesrelated to the lower molecular, unsubstituted PAHs are a good measure ofpetrogenic pollution in the southern Baltic.