The investigation of influence of different types of osmotic stress (hypo- and hyperosmotic) on the composition of vacuolar membrane lipid fatty acids of red beet root (Beta vulgaris L., variety Bordeaux) was conducted. Noteworthy, the plenty intensive stress impact didn't cause the conventional nonspecific reaction bound up with the increase of the unsaturated fatty acid content regulating membrane microviscosity. This feature apparently can be explained with the location and biochemical characteristics of the scrutinized membrane. Some reliable increases of the content of the short-chain saturated fatty acids (C14:0+C15:0) under hyper osmotic stress and the content of the long-chain saturated fatty acids (C22:0+C23:0) under both types of osmotic stress were found. It was proposed that the revealed changes in the content of saturated fatty acids of red beet root vacuolar membrane lipids were specific, and corresponding fatty acids were the most sensitive to osmotic stress impact