Seventeen patients with a more than 5-month-history of angina pectoris were allocated a diet for 4 weeks. The diet was supplemented with 6.15 g of omega 3-polyunsaturated fatty acids (PUFA) in 125 g canned Far-Eastern sardine. This increased the proportion of eicosapentaenic (EPA) and docosahexaenic acids from 1.28 +/- 0.72 to 9.02 +/- 2.83% and from 2.48 +/- 0.91 to 6.54 +/- 2.01%, respectively; p = 0.0003) in the total serum lipid fraction. The levels of omega 6-PUFA decreased due to linoleic acid (from 24.9 +/- 3.9 to 19.7 +/- 5.2%, p = 0.0014). The EPA/arachidonic acid ratio rose from 0.23 +/- 0.11 to 1.76 +/- 0.58 (p < 0.001). The levels of triglycerides decreased by 36.4% (from 162.3 +/- 55.2 to 103.9 +/- 42.4 mg/dl; p < 0.0005); those of very low density lipoproteins and total cholesterol by 36 and 6.8%, respectively (from 32.5 +/- 11.0 to 20.8 +/- 8.5 mg/dl; p < 0.0005 and from 234.8 +/- 43.2 to 218.4 +/- 39.7 mg/dl; p < 0.05, respectively). The concentrations of high density lipoproteins remained unchanged. Thus, a short-term supplementation of canned Far-Eastern sardine to the diet of patients with CHD caused a substantial changes in blood fatty acid composition and favourable shifts in the levels of lipids and lipoproteins. This allows the Far-Eastern sardine to be regarded as a valuable source of omega 3-PUFA which can be used in the secondary prevention of coronary heart disease.