Abstract: The fatty acids were determined, analyzed and compared at the same time in twenty-eight forages. Alpha linolenic acid was the most abundant fatty acid in the forage, making up to 43.78% of the fatty acids. The polyunsaturated fatty acids comprised 54.71% of the fatty acids, and 95.18% of the unsaturated fatty acids, indicating that the unsaturated fatty acids in the forage were dominated by the polyunsaturated fatty acids that had double bonds or more. In the grasses, Lolium multiflorum and Pennisetum had a high alpha linolenic acid content. In L. multiflorum the content was 69.9%, in P. purpureum cv. N51 it was 67.6%, in P. purpureum cv. Red it was 62.2%, and in P. americanum×P. purpureum it was 61.0%. There was no significant difference in the content of alpha linolenic acid between Gramineae and Leguminous forages.