This study was carried out to investigate the concentrations and potential sources of the polycyclic aromatic hydrocarbons (PAHs) in sludge of 14 wastewater treatment plants (WWTPs). Sludge samples were collected from 2 municipal WWTPs, 11 industrial WWTPs, and 1 sanitary landfill leachate treatment plant within the city of Bursa, Turkey during the summer of 2008. Ultrasonication was applied for extraction and gas chromatography–mass spectrometry was used to analyze the PAH contents of the samples. Twelve of the 16 EPA-listed PAH compounds were determined. Total PAH concentrations (P12 PAHs) determined in all of the sludge samples ranged from 1,781 to 19,866 lg/kg dry matter (dm). The sum of 8 of the 11 EU PAHs varied between 1,481 and 17,314 lg/kg dm, and 3 of the samples exceeded the proposed EU limit for land application. One of the automotive industry sludges contained the highest level of PAHs, followed by one of the municipal sludges. The average sum of 5- and 6-ring PAH compounds in all of the sludge samples amounted to almost 65% of the total PAHs. The diagnostic ratios of specific PAHs were calculated to determine the dominant sources for the PAHs in the sludge samples.