Adipose tissues from the 12th and 13th rib interface were sampled at weaning (324 cattle) and slaughter (310 cattle). The animals were progeny from Hereford dams sired by Angus, Belgian Blue, Hereford, Jersey, Limousin, South Devon and Wagyu. Fatty acid composition of the triacylglycerol fraction at both stages was measured by gas-liquid chromatography. Estimates of heritability and genetic and phenotypic correlations at weaning and slaughter were computed by restricted maximum likelihood using a sire model in both univariate and multivariate analyses. Results indicated that generally, there were strong, positive genetic correlations between fatty acids at weaning and slaughter (as high as 0.98). Phenotypic correlations were however, low and poor (0.04 to 0.44). Heritability (h2) estimates at weaning were low to moderate, ranging from 0.0 to 0.31. However, at slaughter, h2 estimates were generally higher than at weaning: Stearate, oleate and total monounsaturates had h2 estimates of 0.43, 0.37 and 0.40, respectively. Other carcass traits such as marbling score and melting point of fat had h2 estimates of 0.20 and 0.52, respectively. Significant breed, sex and location differences in fatty acid composition were also observed at weaning and slaughter.