The fatty acid patterns of oils, blood plasma and erythrocyte lipids from 28 children in the Shaanxi province of the People's Republic of China were determined by capillary gas liquid chromatography. The main source of fat in this region is rapeseed oil. The analysis of locally available rapeseed oil shows a high erucic acid content (mean 43.83%, range 33.91-50.48%). According to protocol data, about 3% of the daily nutrient energy is provided by erucic acid. Despite a low fat intake in Chinese children, the composition of the fatty acids of the fractions analyzed showed normal patterns. However, erucic acid was found in all fractions analyzed. Data on erucic acid in human tissue are scarce. Although there are no indications of erucic acid toxicity in man, it is known to cause cardiac lipidosis and necrosis in rats. The question remains open if erucic acid aggravates selenium deficiency symptoms which are known to be associated with Keshan disease, an endemic cardiomyopathy.