Semimembranosus muscle samples from 795 Large White heavy pigs were used to determine their intramuscular fatty acid composition and to estimate the heritability and the genetic correlations of these traits. Muscle fatty acids showed heritability estimates of low-to-moderate magnitude, ranging from 0.157 for total fatty acids to 0.237 for docosahexaenoic acid. Only small differences in heritability appeared among fatty acids based on their chain length, saturation and double bond position. Omega-6 polyunsaturated fatty acids showed positive genetic correlations with carcass lean % (0.563 ± 0.005) and loin thickness (0.438 ± 0.005) while being negatively related to backfat thickness measured both by calibre (-0.225 ± 0.008) and Fat-O-Meat'er (FOM) apparatus (-0.603 ± 0.004). Interestingly, the monounsaturated fatty acid class was not correlated with carcass measures and presented only a weak positive genetic correlation with intramuscular fat (0.145 ± 0.002). This result suggests that in heavy pig breeds monounsaturated fatty acids in muscle could be selected for without interfering with carcass traits.