The absolute configuration of the neoclerodane glycoside amarisolide, presented here as the monohydrate, C26H36O9*H2O, has been determined by association with the known configuration of the glucose moiety. Its structure was established as 2beta-(O-beta-D-glucopyranosyl)neocleroda-3,13(16),14-trien-15,16-epoxy-18,19-olide. Extensive hydrogen bonding among the hydroxyl groups of the sugar moiety forms layers which are interconnected by water molecules.