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Sewage discharge could be a major source of polycyclic aromatic hydrocarbons (PAHs) in thecoastal waters.Stonecutters Island and Shatin Sewage Treatment Works (SCISTW and STSTW)in Hong Kong adopted chemically enhanced primary treatment and biological treatment,respectively.This study aimed at (1) determining the removal efficiencies of PAHs,(2) comparingthe capabilities in removing PAHs,and (3) characterizing the profile of each individual PAHs,inthe two sewage treatment plants (STPs).Quantification of 16 PAHs was conducted by a GasChromatography.The concentrations of total PAHs decreased gradually along the treatmentprocesses (from 301 ± 255 and 307 ± 217 ng/L to 14.9 ± 12.1 and 63.3 ± 54.1 ng/L in STSTW andSCISTW,respectively).It was noted that STSTW was more capable in removing total PAHs thanSCISTW with average total removal efficiency 94.4％ ± 4.12％ vs.79.2％ ± 7.48％ (p ＜ 0.05).Theremoval of PAHs was probably due to sorption in particular matter,confirmed by the higherdistribution coefficient of individual and total PAHs in solid samples (dewatered sludge contained92.5％ and 74.7％ of total PAHs in SCISTW and STSTW,respectively) than liquid samples (finaleffluent-total contained 7.53％ and 25.3％ of total PAHs in STSTW and SCISTW,respectively).Despite the impressive capability of STSTW and SCISTW in removing PAHs,there was still aconsiderable amount of total PAHs (1.85 and 39.3 kg/year,respectively for the two STPs) beingdischarged into Hong Kong coastal waters,which would be an environmental concem.