Three new bromotyrosine-derived alkaloids, aplysinamisines I [4], II [5], and III [6], were isolated from the sponge Aplysina cauliformis collected in Puerto Rico and their chemical structures elucidated on the basis of spectroscopic methods. Compounds 4-6 showed marginal antimicrobial activity, and aplysinamisines II [5] and III [6] displayed modest cytotoxicity.