Three new chlorinated metabolites, namely 3-(3,3-dichloro-2-methylpropyl)-6-(3,3-dichloro-2-methyl-propylidene)-1,4-dimethylpiperazine-2,5-dione (3), 1-methyl-3-(3,3,3-trichloro-2-methylpropyl)-6-(3,3,3-richloro-2-methylpropylidene)piperazine-2,5-dione (4) and 5,5-dichloro-4-methyl-2-[methyl(4,4-dichloro-3-methyl-1-oxobutyl)amino]-N-(thiazol-2-ylmethyl)pentanamide (8), have been isolated from collections of Dysidea herbacea from the southern region of the Great Barrier Reef. The relative and absolute stereochemistry of (4) was determined by X-ray crystallographic analysis.