The composition of lipids, phospholipids and fatty acids from three moss species was studied. The major phospholipid classes were phosphatidylglycerol, phosphatidylcholine and phosphatidylethanolamine. Fatty acid composition was examined by capillary GC-MS in the neutral, glyco- and phospholipid fractions; eighty-five fatty acids were identified. The identification of acetylenic acids was achieved using an original technique. The neutral fraction from Dicranum polysetum yielded 72% acetylenic acids amongst which some unusual rarely occurring acids were identified, i.e. 9a,12–18:2, 6a,9,12,15–18:4, 8a,11,14–20:3 and 5a,8,11,14–20:4. The presence of 16:4 ( n-3) in mosses was identified for the first time.