Muscle tissue of the queen crab, Chionoecetes opilio, contained 0.75% lipid, 78.8% of which was phospholipid (chiefly choline phosphatides) and the balance mainly cholesterol. Viscera contained 13.6% lipid, the bulk of which was triglyceride. Fatty acid composition was generally similar to that of other marine species. However, 20:5ω3 was the major polyunsaturate (rather than the more usual 22:6ω3) and within the 18:1 series, the ω7 isomer was present in unusually large quantities.