As energy reserves in the body tissue of mature liver flukes var. Fasciola gigantica from the bile ducts of Nigerian Zebu cattle the following percentages were found: protein 60.29, lipid 11.92, carbohydrate 7.0. The analysis of the lipid fractions showed the following composition: 47% phospholipids (63% phosphatidyl choline, 28% phosphatidyl serine, 9% lysophosphatidyl choline) and 22% triglycerides, 16% fatty acids, 6% cholesterol, 5% monoacyl glycerol, and 4% cholesterol ester.