1,19-Dideoxyfistularin 3 [3] and 11-hydroxyaerothionin [6], two new bromotyrosine-derived metabolites, have been isolated from the verongid sponge Pseudoceratina durissima, along with the known compounds aerothionin [1] and homoaerothionin [2]. Marine sponges in the order Verongida are distinct both chemically and biologically from those in other orders of the Porifera (1,2). All genera of the Verongida chemically examined so far contain secondary metabolites that are derived from bromotyrosine or from chlorotyrosine (3,4). In such metabolites the side chain has been converted into a variety of nitrogenous groups while the aromatic ring has either been retained or has undergone rearrangement or partial reduction. Interest in the sponge Pseudoceratina durissima Carter (Family Aplysinellidae) collected from the Great Barrier Reef was stimulated by the potent in vitro antimicrobial activity of its CH₂Cl₂ extract. Separation of the crude extract on Sephadex LH-20 gave a single antimicrobial fraction that was purified by cc on Si gel to give the known metabolites aerothionin [1] (5) (0.34%) and homoaerothionin [2] (6) (0.11%) and two new metabolites, 11,19-dideoxyfistularin 3 [3] (0.33%) and 11-hydroxyaerothionin [6] (0.09%). Aerothionin [1], whose absolute configuration has been established (7), and homoaerothionin [2] were identified from spectral data, including optical rotations, that were identical with literature values (5,6). The structures of 11,19-dideoxyfistularin 3 [3] and 11-hydroxyaerothionin [6] were determined by spectroscopic methods.