Hexabromocyclododecanes　(HBCDs)　are　ubiquitous　contaminants　in　the　environment,　but　little　is　known　on　the　occurrence　and　distribution　of　HBCDs　in　the　background　atmosphere　of　urban　environments.　In　this　study,　air　samples　were　collected　from　four　sites　in　the　city　of　Guangzhou,　a　typical　fast　developing　metropolitan　of　South　China,　for　quantifying　the　concentration　levels,　diasteroisomer　profiles,　gas-particle　distribution　and　enantiomeric　fractions　of　HBCDs.　The　results　showed　that　the　measured　mean　atmospheric　HBCD　concentrations　ranged　from　0.69　to　3.09　pg/m(3),　which　were　similar　to　those　reported　from　remote　or　urban　sites　of　the　U.S.,　but　were　significantly　lower　than　those　of　Europe.　The　analysis　on　diastereoisomer　profiles　indicated　that　alpha-HBCD　(59-68%)　was　the　dominant　isomer　and　beta-HBCD　was　a　minor　isomer　in　all　air　samples,　which　appeared　to　be　different　from　commercial　products.　A　large　variable　percentage　of　HBCDs　(69.1-97.3%)　are　existed　in　the　particle　phase,　suggesting　that　long-range　tansport　of　HBCDs　might　be　occur　in　some　environmental　conditions.　The　results　of　enantiomeric　fractions　indicated　that　beta-　and　gamma-HBCD　were　racemic　mixtures　in　the　tested　air　samples　and　that　(-)-alpha-HBCD　was　slightly　enriched　in　the　typical　urban　site,　implying　that　the　HBCDs　in　these　studied　sites　might　be　a　mixture　of　emissions　from　both　local　sources　and　soil-air　exchange.