Several marine sponges from Okinawan waters have been examined for bioactive compounds. Further investigation with Polyfibrospongia sp. which have already yielded novel metabolites gave new hennoxazoles (6–9), of which 7 was moderately cytotoxic. Echinoclathria sp. furnished new pyridine alkaloids (10–12), two of which showed immunosuppressive activity. A sponge identified to be Dysidea herbacea afforded cytotoxic 20,24-dimethyldeoxoscalarin-3-one (14) along with known diterpenes. Two cytotoxic dimers (15,16) of a sesquiterpene have been isolated from Halichondria sp. Mytiloxanthin derivatives (18,19) were the major pigments of Phakellia stelliderma. A new species of the family Niphatidae gave highly cytotoxic polyacetylenes (20–26). © 1994 IUPAC