Changes in fatty acid composition in both fresh and frozen sardine during mixed smoking (2 h at 30-degrees-C and 45 min at 75-degrees-C) were studied. After extraction, the lipids from unsmoked and smoked sardine were separated into the three main fractions (triglycerides, phospholipids, and free fatty acids) by thin-layer chromatography; the fatty acids were then analyzed using gas chromatography. Oxidation during smoking brought about losses in the proportion of the long-chain n-3C20 and C22 fatty acids, as determined by increases in the peroxide value and in the 2-thiobarbituric acid index. On the other hand, the above polyunsaturated long-chain fatty acids in some conditions increased in frozen sardine, because of extraction-related effects caused by weakening of the protein-lipid linkages.