Marine Algae and Marine Environment Discipline, Central Salt and Marine Chemicals Research Institute, G. B. Marg, Bhavnagar-364 002, India E-mail : salt@csir.res.in Fax : 91-278-566970/567562 Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Jadavpur, Kolkata-700 032, India Manuscript received 1 June 2001, revised 18 March 2002, accepted 10 May 2002 An inseparable mixture of nitrogenous glycerolipids was isolated from the Dragendorff positive fraction of the methanol extract of the marine green alga Ulva fasciata, collected from Okha (22��28' N, 69��05' E) at Gujarat (India) coast. Monoacylglyceryl-N,N,N��trimethylhomoserine having 16 : 0 and 18 : 2 fatty acid residues were found to be the predominant components of this fraction. This is the first report of their occurrence in this source.