The synthesis of fatty acids is important for many house keeping functions such as the formation of cell membranes and as energy storage This process occurs mostly in the adipose tissues and liver of monogastric animals. The regulation of fatty acid biosynthesis in monogastric animals such as human and rat have been studied intensively. Several lines of experimental evidences have shown that fatty acid biosynthesis is dependent on the nutritional state of the animal and other hormonal influences, such as insulin and glucagon. However the molecular regulation of fatty acid biosynthesis is relatively unknown in ruminants. Ruminants are large mammals that have a predominantly herbivorous diet and therefore have a very different metabolism to monogastric animals. Although a large percentage of ruminant feed is carbohydrate, very little of these dietary carbohydrates are available for de novo fatty acid biosynthesis and therefore many of the enzymes involved in the conversion of glucose to fat such as ATP citrate lyase may be down-regulated as a mean of physiological adaptation for glucose conservation. ATP citrate lyase (ACLY) is a lipogenic enzyme that catalyses the cleavage of cytosolic citrate into acetyl CoA and oxaloacetate and it is unique to the fatty acid biosynthesis pathway The molecular regulation of the bovine ACLY gene is unknown, however approximately 10 Kb of bovine ACLY gene has been sequenced and characterised. To investigate the molecular regulation of the bovine ATP citrate lyase gene, several experimental methods were used in this study such as reporter gene assays and electrophoretic mobility shift assays.