Proximate compositions, fatty acid profiles, and total amino acid compositions of the muscle and liver of Patagonian toothfish Dissostichus eleginoides were studied. Lipid contents of the muscle and liver of the fish were 22.3% and 35.3%, respectively. Protein content was higher in the fish muscle (12.8%) than in the liver (8.7%). Moisture content was also higher in the muscle (63.6%) than in the liver (49.8%). The prominent fatty acids in the total lipids of the fish muscle and liver were 18:1n-9, 16:0, 20:1n-9, 16:1n-7, 22:6n-3 (docosahexaenoic acid, DHA), 18:1n-7, 22:1n-11, 18:0, and 20:5n-3 (eicosapentaenoic acid, EPA). The fish muscle and liver contained approximately 1,000 to 2,500 mg of DHA and 400 to 600 mg of EPA per 100 g of tissue. Therefore, the fish muscle and liver are good sources of n-3 polyunsaturated fatty acids. On the other hand, the total amino acid content of the fish was 11.7 g/100 g muscle and 6.53 g/100 g liver. The prominent total amino acids profiles in the fish muscle and liver were glutamic acid, lysine, aspartic acid, leucine, and alanine, which are similar to those in other fishes.