An　analytical　method　has　been　developed　and　validated　for　the　determination　of　six　estrogens　and　estrogen　mimics,　namely　estriol　(E3),　bisphenol　A　(BPA),　17　beta-estradiol　(E2),　estrone　(E1),　ethynyl　estradiol　(EE2)　and　dienestrol　(DIE),　with　frequent　occurrence　in　the　natural　environment.　Solid　phase　extraction　coupled　with　liquid　chromatography　tandem　mass　spectrometry　(SPE-LC-MS/MS)　using　electrospray　ionization　(ESI)　in　a　negative　mode　was　applied　to　concentration,　identification,　and　quantification　of　estrogens　and　estrogen　mimics.　The　SPE　conditions　were　optimized　as　the　selection　of　C18　as　cartridges　and　MeOH　as　an　eluent,　and　the　control　of　solution　pH　at　9.0.　The　method　was　validated　by　satisfactory　recoveries　(80-130%)　and　intra-day　and　inter-day　precision　(＜18.4%,　as　relative　standard　deviation),　and　excellent　linearity　for　calibration　curves　(R-2　＞　0.996).　The　limits　of　detection　(LODs)　for　six　target　estrogenic　compounds　ranged　between　2.5　and　19.2　ng/L.　The　effects　of　matrix　background　on　the　determination　were　evaluated　in　terms　of　LODs,　LOQs,　analyte　recovery,　and　slopes　of　calibration　curves　in　five　different　water　matrices.　Matrix　effects　by　tap　water　were　negligible.　However,　both　matrix　suppression　and　enhancement　(i.e.,　E3,　E1,　DIE)　were　observed　in　surface　water　and　wastewater.　The　positive　correlation　between　LODs　and　TOC　in　various　water　matrices　indicated　the　negative　effect　of　organic　pollutants　on　the　method　sensitivity.　The　sum　of　target　estrogenic　compounds　in　environmental　samples　were　within　17-9462　ng/L.