Aurantosides D-F (4-6), new polyene tetramic acids comprising an N-trisaccharide unit, have been isolated from the marine sponge Siliquariaspongia japonica. Their structures were determined by spectral and chemical methods. A reinvestigation of NMR data of the previously isolated aurantosides A and B led to revision of the geometry of the terminal double bond. Aurantosides exhibit potent antifungal activity against Aspergillus fumigatus and Candida albicans.