Chemical investigation of the cytotoxic EtOH extract of the marine tunicate Eudistoma album led to the isolation of three brominated beta-carbolines which were characterized by their spectral data. Two of them, eudistomin E, which is already known for its potent antiviral activity, and the novel compound eudistalbin A [1], were shown to possess cytotoxic activity (ED50 less than 5.0 ng and 3.2 micrograms/ml respectively) in vitro against the growth of KB human buccal carcinoma cells. The third compound, eudistalbin B [2], is a new inactive natural product.