Recent　large　epidemiological　studies　demonstrated　benefit　of　oral　contraceptives　in　reducing　cancer　risk,　and　our　analysis　also　showed　molecular　and　cellular　similarities　between　embryo　implantation　and　CTCs　adhesion-invasion　to　endothelium.　We　here　hypothesize　that　abortion　traditional　Chinese　medicine　(TCM)　may　serve　well　for　pre-metastatic　chemoprevention.　To　test　the　hypothesis,　we　selected　the　safe　and　well-known　abortifacient　TCM　Murraya　paniculata　and　identified　a　most-promising　extracted　fraction　G　(containing　flavonoids　and　coumarins)　from　its　many　raw　ethanol/dichloromethane　extracts　by　using　the　bioactivity-guided　fast　screen　assay.　G　showed　free　radical　scavenging　effect,　and　specifically　inhibited　both　embryo　implantation　to　human　endometrial　bed　and　cancer　HT29　cells　to　human　endothelium　in　a　concentration-dependent　manner　(1-30　mu　g/mL)　without　significant　cytotoxicity　demonstrated　by　its　high　adhesion　inhibition　ratio.　The　inhibition　may　result　from　its　down-regulation　on　expression　of　integrin　beta　1　and　a6,　and　CD44　on　HT29　cells,　as　well　as　E-selectin　on　endothelial　cells.　Furthermore,　G　inhibited　invasion　and　migration　of　HT29　cells.　Pretreatment　followed　by　one-month　oral　administration　of　G　to　the　immunocompetent　mice　inoculated　with　mouse　melanoma　cells　produced　significant　inhibition　on　lung　metastasis　without　marked　side　effects.　Collectively,　this　paradigm-shifting　study　provides,　for　the　first　time,　a　new　strategy　to　discover　safe　and　effective　pre-metastatic　chemopreventives　from　abortion　TCM.