Levels,　composition　profiles　and　sources　of　polycyclic　aromatic　hydrocarbons　(PAHs)　were　analyzed　in　55　surface　soil　samples　collected　from　Shanghai　urban　districts.　The　total　concentrations　of　22　PAHs　(Sigma　PAHs)　ranged　from　442　to　19,700　mu　g　kg(-1),　with　a　mean　of　3780　mu　g　kg-1,　and　the　sum　of　16　priority　PAHs　(Sigma　16PAHs)　varied　from　347　to　17,900　mu　g　kg(-1),　with　a　mean　of　3290　mu　g　kg(-1),　and　the　seven　possible　carcinogenic　PAHs　(Sigma　7CarPAHs)　accounted　for　36-58%　of　Sigma　16PAHs.　Among　different　functional　areas,　the　higher　level　of　PAHs　was　found　in　the　roadside,　followed　by　greenbelt,　commercial　district,　park,　and　residential　district.　The　composition　of　PAHs　was　characterized　by　the　high　molecular　weight　PAHs.　among　which　fluoranthene,　pyrene,　benzo[b]fluoranthene　and　chrysene　were　most　dominant　components.　A　correlation　analysis　showed　that　there　was　relatively　good　correlation　among　the　individual　PAHs,　but　the　contents　of　PAHs　were　poorly　correlated　with　soil　total　organic　carbon　(TOC).　A　principal　component　analysis　and　PAHs　isomeric　ratios　indicate　that　PAHs　in　Shanghai　urban　soil　mainly　originated　from　combustion.　The　toxic　assessment　suggested　that　soil　PAHs　exposure　is　medium　carcinogenic　at　present　level.　(C)　2009　Elsevier　Ltd.　All　rights　reserved.