The fruits of Melia species in Asia are somewhat poisonous, but regarded as anthelmintic, antifeedant, antifebrile and diuretic. They are employed to treat fever, delirium, hernia and uterine illness. Recently we isolated a potent insecticidal compound against larvae of Bombyx mori from the fruits of Melia toosendan, The active principle was isolated by repeated column chromatography and recrystallization as a needle crystal. The structure was elucidated by ¹H-NMR , ^(13)C-NMR , MS and other spectroscopic data of acetylated compounds. This presentation describes isolation, purification, structure elucidation and insecticidal activity of this compound.