The pigments of the polychaete Sabella penicillus L. were reinvestigated. In addition to zeaxanthin and traces of lutein, a series of carotenoids which may represent steps in the formation of canthaxanthin have been found. These are β-carotene, isocryptoxanthin, echinenone, 4-hydroxy-4′-keto β-carotene and canthaxanthin. No astaxanthin was found. In two other sabellids, Myxicola infundibulum (Renier) and Megalomma vesiculosum (Montagu), astaxanthin was confirmed as the major pigment and the presence of echinenone was established. Attention was drawn to the similarity of the pigments of Sabella penicillus with those of other invertebrates and it has been suggested that in invertebrates a common pathway for the formation of canthaxanthin may exist.