A novel 20-membered macrolide, zampanolide (3), has been isolated together with latrunculin A (1) from a different collection of the sponge which previously yielded 1 and laulimalide (2). The gross structure of 3 was determined by 2D NMR and partial stereochemistry by NOE analysis. It is a highly unsaturated 20-membered macrolide containing an uncommon carbinol amine functionality. Zampanolide showed potent cytotoxicity against several tumor cell lines.