The sea hare Aplysia punctata from Sancti Petri (Cádiz, Spain) contains four new unusual acetates of linear polyhalogenated monoterpenes (5-8) together with four known cyclic derivatives (1-4). The structures were elucidated by interpretation of spectral data. It is suggested that the new constituents of A. punctata might be biotransformation products. Compounds 6-8 showed significant in vitro cytotoxicity against four tumor cell lines.