The excess of coronary heart disease in Indian Asians compared with Europeans is unexplained by conventional risk factors, although the high prevalence of diabetes may play a part. To explore the contribution of diet we compared the fatty acid composition of erythrocyte membrane phospholipid and plasma triglyceride in 36 Gujarati Asians and 24 Europeans with non-insulin-dependent diabetes. Erythrocytes from Asian subjects contained higher proportions of linoleic, dihomogammalinolenic, and arachidonic acids, and lower proportions of oleic and n-3 series fatty acids; triglycerides contained higher linoleic and lower oleic acid levels. For example, mean percentage (SE) of oleic acid (18:1n-9) in erythrocytes was 16.7 (0.2) in Asians and 20.5 (0.6) in Europeans (p = 0.0001), and total n-6:n-3 ratio was, respectively, 12.8 (0.7) and 6.7 (0.7) (p = 0.0001). A high dietary intake of linoleic acid may not be cardioprotective unless balanced by significant intakes of oleic and n-3 series fatty acids, at least in diabetic Indian Asians. By itself, the conventional recommendation to substitute polyunsaturated for saturated fat in the diet may be inadequate to reduce thrombogenesis, and the overall balance of fatty acids, including monounsaturates, should be considered.