A total of 62 topsoil samples (0-10 cm) were gathered from Istanbul's urban town and investigated for 8 polycyclic aromatic hydrocarbons (PAHs). The main aim of the study was to assess the origins of PAHs using diagnostic ratios of selected pairs of PAH congeners in soil of Istanbul. The range of total of 8 PAHs (sigma(8)PAH) concentrations was found as 0.001-5.941 mu g g(-1). Generally higher concentrations were determined at locations being crowded towns and close to busy traffic. Most stations have both pyrolytic and petrogenic origins of PAHs. This study is the first research on the origin of PAHs in Istanbul urban soils and will be database for further studies.