Rats were fed for 6 weeks a diet containing either sunflower oil or linseed oil. In each case, blood serum was subsequently collected and added to two media which were then used to grow cardiomyocytes. Under these conditions, the incorporation of omega 6 and omega 3 polyunsaturated fatty acids shows similar trends in hearts and cultured cardiomyocytes. The content of C22-unsaturated fatty acids was lower in the myocytes than in the hearts but the ratio of acids of the omega 6 series to those of the omega 3 series was similar.