Abstract: Effects of increasing dietary energy by supplementation of soy oil on intramuscular fat (IMF) content, fatty acids composition of IMF and backfat in pigs were investigated. Thirty six Duroc×Landrace×Large White female pigs at a mean initial body weight of 40 kg were equally and randomly assigned into three treatment groups. The digestible energy of the diets was 1282, 1424 and 1566 MJ·kg-1 for three groups respectively and the energy level of diet was adjusted mainly by the supplementation of soy oil. Five pigs of each group were slaughtered at the body weight of about 90 kg. Longissimus dorsi muscle (LM) and backfat were sampled for determination of IMF content and fatty acids composition. There was no significant effect of dietary energy level on IMF content in LM (P>005). The percentages of most saturated (SFA) and monounsaturated fatty acids (MUFA) and of most polyunsaturated fatty acids (PUFA) decreased and increased significantly (P<005) respectively both in LM and backfat as the dietary energy level increased. The IMF content in LM was negatively correlated with the percentages of C20∶0, C18∶3n6, C20∶4n6, C22∶5n3 and C24∶1. Most fatty acids in LM were positively correlated with those in backfat while there were no significant relationships for C18:3n6,CLAc9t11,C20∶0,C20∶4n6,C22∶5n3 and C24∶1 between the two tissues. In general, SFAs were positively correlated with MUFAs and both of them were negatively correlated with PUFAs while PUFAs were positively correlated with each other in both tissues. In conclusion, increasing dietary energy level by supplementation of soy oil is an effective way to improve IMF fatty acids composition without decreasing IMF content, thus improving the nutritional value of pork without deleteriously affecting meat quality.