Adipose tissue becomes more saturated and less unsaturated with age (Kemp et al., 1981). Desaturation of stearic acid to the oleic acid is catalysed by stearoyl-CoA desaturase (SCD) and increasing the degree of desaturation of lamb is likely to be beneficial in terms of human nutrition. By altering the levels of ovine SCD mRNA, the supply of oleic acid to the tissue could be manipulated, resulting in a practical method of changing the fatty acid profile of the animals meat. Previous work in our laboratory has shown variability between adipose tissue depots in their expression of SCD and that this variability is associated with changes in oleic acid content (Daniel et al, 2004). Such differences in SCD expression between depots implies that there may be even larger variation in SCD expression between breeds. A sheep breed with particularly high level of SCD mRNA could then be exploited through breeding programmes to produce animals with increased desaturase activity and therefore increased oleic acid content. Three sheep breeds, Texel, Beulah and Soay, were therefore used to study the influence of breed and age on SCD expression.