A new lycorine derivative LT1 (4) was isolated from the aerial part and bulbs of Lycoris traubii Hayward (Amaryllidaceae). Its structure including absolute configuration was established by spectroscopic analysis and semi-synthesis to be 1-O-(3'S)-hydroxybutanoyllycorine. Some lycorine ester derivatives including LT1 were examined for their inhibitory activity against Trypanosoma brucei brucei, the