The qualitative and quantitative carotenoid composition of seven prasinophytes (eight clones) have been examined by chromatographic (TLC and HPLC) and spectroscopic methods (VIS, CD and mass spectra).The prasinophytes studied fall into two pigment types: (A) those producing common green algal carotenoids (~,13,-carotene, p,s-carotane, lutein, zeaxanthin and the epoxides violaxanthin and neoxanthin) and (B) prasinophytes synthesising carotenoids peculiar to this algal class (prasinoxanthin, anhydroprasinoxanthin, uriolide, anhydrouriolide, micromonal, anhydromicromonal, micromonol, anhydromicromonol and dihydrolutein), where prasinoxanthin is a major carotenoid.Mantoniella squamata (clone 2) was grown under both low and high light intensity, revealing differences in carotenoid composition. Lutein together with lesser amounts of zeaxanthin and its epoxides were only detected at high light intensity.Three previously unidentified carotenoids were identified as prasinoxanthin (xanthophyll K), micromonal and dihydrolutein.