The heart phospholipid content and fatty acid composition were examined in adult rats after four weeks of feeding lipid-supplemented diets (20 g % w/w) containing sunflower oil-lard (1:1) mixture (SL group) or margarine (M group). Our results showed a decreased cardiolipin content and distribution in both experimental groups and an increased lysophosphatidylcholine and phosphatidylcholine content and distribution in the SL group with a tendency to lower phosphatidylcholine/phospatidylethanolamine ratio in both experimental groups. In the SL group, the content of saturated fatty acids was higher and that of monounsaturated fatty acids was lower than in the control group. The M group showed inverse results. The content of saturated fatty acids was lower and that of monounsaturated was higher than in the control group. Polyunsaturated n-6 fatty acids were decreased in both experimental groups and n-3 fatty acids were increased in the M group. Feeding lipid-supplemented diets reduced n-6/n-3 and 20:4/22:6 ratios in the M group. The polyunsaturated/saturated fatty acid ratio was lower in the SL and higher in indicating the M group than in the control group. Our results are in agreement with the other reports indicating that the heart is sensitive to diet-induced lipid alterations.