Algae from cold water (Canada) and warm water (China) were analyzed for their total lipid content, and for their fatty acid (FA) composition and content. The major findings are that FA from Canadian algae are generally richer in polyunsaturated FA (PUFA), with a higher n-3/n-6 FA ratio, and a higher degree of total unsaturation. The 18 C, 4 double bonds FA (18 : 4 stearidonic acid, morotic acid as synonym) was detected in greater amounts in cold water samples. The high levels of total PUFA, and especially of n-3 FA in Canadian algae, suggests their possible utilizations for nutritional purposes. Copyright © 2005 John Wiley & Sons, Ltd.