The work in this book details the phytochemical and biological investigations of one species of Euphorbiaceae,Sapium baccatum. Some works had been reported previously on this species but this species grown in Bangladesh has not been studied extensively. The leaves of Sapium baccatum were cold extracted with methanol. The cold methanol extract was fractionated into three fractions and then subjected to column chromatography. The chemical investigation of petroleum ether extract of Sapium baccatum led to the isolation of six metabolites. All metabolites were identified and named as Lupeol, Betulin, Taraxerol, Taraxerone, Stigmasterol and ?-sitosterol respectively.The crude methanol extract showed poor to mild and other three extracts exhibited no activity, the six column fractions of petroleum ether extract and the four pure compounds exhibited poor antimicrobial activity against most of the test organisms. Crude Methanol, column fraction F-7, F-10 & F-12 of Petroleum ether extract and pure compound-1 and 4 showed quite potent activity in brine shrimp lethality bioassay.These positive result suggested that these may be contain antitumor or pesticidal compounds.