Phytochemical investigation of the whole plant of Amberboa ramosa led to the isolation of six sesquiterpene lactones which could be identified as $8{alpha}$-hydroxy-$11{eta}$-methyl-$1{alpha}H,;5{alpha}H,;6{eta}H,;7{alpha}H,;11{alpha}H-guai-10(14)$, 4(15)-dien-6, 12-olide(2), $3{eta},;8{alpha}-dihydroxy-11{alpha}-methyl-1{alpha}H,;5{alpha}H,;6{eta}H,;7{alpha}H,;11{eta}H-guai-10(14)$, 4(15)-dien-6, 12-olide (2), $3{eta},;4{alpha},;8{alpha}-trihydroxy-4{eta}(hydroxymethyl)-1{alpha}H,;5{alpha}H,;6{eta}H,;7{alpha}H-guai-10(14)$, 11(13)-dien-6, 12-olide (3), $3{eta},;4{alpha},;8{alpha}-trihydroxy-4{eta}-(chloromethyl)-1{alpha}H,;5{alpha}H,;6{eta}H,;7{alpha}H-guai-10(14)$, 11(13)-dien-6, 12-olide(4), $3{eta},;4{alpha},;dihydroxy-4{eta}-(hydroxymethyl)-1{alpha}H,;5{alpha}H,;6{eta}H,;7{alpha}H-guai-10(14)$, 11(13)-dien-6, 12-olide(5), $3{eta},;4{alpha}-dihydroxy-4{eta}-(chloromethyl)-8{alpha}-(4-hydroxymethacrylate)-1{alpha}H,;5{alpha}H,;6{eta}H,;7{alpha}H-guai-10(14)$, 11(13)-dien-6, 12-olide (6) by spectroscopic methods. All of them showed inhibitory potential against butyrylcholinesterase.