Loliolide content was determined in 13 marine algae including red, brown and green algae collected from the Black Sea, the Dardanelles and the Aegean Sea. Identification and quantification were performed by gas chromatography-mass spectrometry. The loliolide content in green alga is 1.76 microg g(-1), ranges from 0.14 to 4.35 microg g(-1) in red and from 0.18 to 4.83 microg g(-1) in brown algae. The results obtained are in the same range as previously reported for algae, as well as terrestrial plants. This article represents the first report of loliolide occurrence in green algae.