Pibocin(1) (1), the first representative of marine ergoline alkaloids, was isolated from the Far-Eastern ascidian Eudistoma sp. Its structure and absolute stereochemistry have been established as (8 beta)-2-bromo-6,8-dimethylergoline on the basis of spectroscopic and X-Ray analysis data. Pibocin showed moderate cytotoxic activity against mouse Ehrlich carcinoma cells, (C) 1999 Elsevier Science Ltd. All rights reserved.