Effluents　of　sewage　treatment　plants　(STPs)　are　an　important　source　of　estrogenic　substances　to　the　receiving　water　bodies　affecting　their　ecological　safety.　In　this　study,　steroids,　bisphenol　A　(BPA)　and　phthalates　were　assessed　in　the　secondary　(SE)　and　tertiary　effluent　(TE)　of　three　typical　urban　STPs　in　Beijing　(China).　In　addition,　the　overall　estrogenic　activity　in　these　effluents　was　assessed　by　an　in-vitro　bioassay　(ERE-CALUX).　Results　showed　that　the　concentrations　and　activities　of　estrogenic　compounds　in　TE　were　lower　than　those　in　SE.　The　residual　concentration　of　178-estradiol　(E2)　was　the　highest　among　the　detected　steroids,　accounting　for　51.6　+/-　5.1%　in　SE　and　57.5　+/-　24.8%　in　TE.　The　residual　level　(25.2-41.6　ng/L)　of　BPA　in　effluents　was　significantly　higher　than　that　of　steroids　(0.2-28.8　ng/L).　The　residual　concentration　of　diethyl　phthalate　was　the　highest　among　the　detected　phthalates　accounting　for　47.1　+/-　5.1%　in　SE　and　37.6　+/-　11.5%　in　TE.　Steroids　and　BPA　had　a　higher　removal　rate　(83.5%　and　96.7%)　in　secondary　and　tertiary　treatment　than　phthalates　(68.8%　and　83.1%).　The　hydrophobic　characteristics　of　these　estrogenic　compounds　determined　the　removal　mechanism.　The　removal　of　steroids,　BPA,　dimethyl　phthalate　and　diethyl　phthalate　(LogKow=　1.61-4.15)　mainly　occurred　through　biodegradation　in　the　water　phase,　while　the　removal　of　dibutyl　phthalate,　butylbenzyl　phthalate　and　di(2-ethylhexyl)　phthalate　(LogKow=　4.27-7.50)　mainly　occurred　in　the　solid　phase　after　adsorption　on　and　sedimentation　of　the　suspended　particulate　matter.　According　to　ERE-CALUX,　the　estrogenic　activity　in　the　final　STP　effluents　was　3.2-45.6　ng　E2-equivalents/L,　which　is　higher　than　reported　levels　in　the　effluents　of　European　STPs.　Calculation　of　estrogenic　equivalents　by　using　substance　specific　chemical　analysis　indicated　that　the　dominant　contributor　was　E2　(56.4-88.4%),　followed　by　17　alpha-ethinylestradiol　(EE2)　(4.1-34.8%),　both　also　exerting　a　moderate　risk　to　the　aquatic　ecosystem.　While　the　upgrade　of　treatment　processes　in　STPs　has　efficiently　reduced　the　emission　of　estrogenic　substances,　their　ecological　risk　was　not　yet　phased　out.