Seven blue-green algae, Anabaena cylindrica, A. variabilis, Coccochloris elabens, Cylindrospermum sp., Mastigocladus laminosus, Microcoleus vaginatus and Nostoc sp., synthesize the same three major carotenoids : β-carotene, echinenone and myxoxanthophyll; zeaxanthin is present in small amounts. Lutein could not be detected. β-Carotene represents between 30 and 60% of the total carotenoids present. The carotenoid distribution in blue-green algae and other photosynthetic organisms is discussed.