A chemical investigation of secondary metabolites from the sponge Aiolochroia crassa has been performed and five bromotyrosine derivatives (1-5) were identified. Their structures have been assigned on the basis of spectroscopic analysis, of which araplysillin III (2) and hexadellin C (3) possess new structures. The absolute configurations of dibromotyrosine moieties of 2 were determined by HPLC analysis of derivatized constituent amino acids obtained from acid hydrolysis. The stereochemistry of the spirocyclohexadienylisoxazoline moiety of compounds 1- 3 was deduced from spectroscopic comparison of the same moiety of aerothionin, of which the absolute configuration was previously assigned by X-ray and CD analysis.