Fusaroside (1), a unique trehalose-containing glycolipid composed of the 4-hydroxyl group of a trehalose unit attached to the carboxylic carbon of a long-chain fatty acid, was isolated from the organic extract of fermentation broths of an endophytic fungus, Fusarium sp. LN-11 isolated from the leaves of Melia azedarach. Six known compounds, phalluside (2), (9R*,10R*,7E)-6, 9,10-trihydroxyoctadec-7-enoic acid (3), porrigenic acid (4), (9Z)-2,3-dihydroxypropyl octadeca-9-enoate (5), cerevisterol (6) and ergokonin B (7), were also isolated from this fungus. The glycolipid contains a rare branched long-chain fatty acid (C(20:4)) with a conjugated diene moiety and a conjugated ketone moiety. The structure of the new compound 1 was elucidated by spectroscopic methods (1D and 2D NMR experiments, MS) and chemical degradations. The metabolites 1-5 were shown to have moderate to weak active against the brine shrimp larvae. To our knowledge, this is the first report of isolation of the first representative of a new family of glycolipids from natural sources.