The acyl-CoA binding protein (ACBP) is a 10kDa intracellular protein expressed in all eukaryotic species and mammalian tissues investigated. It binds acyl-CoA esters with high specificity and affinity and is thought to act as an intracellular transporter of acyl-CoA esters between different enzymatic systems; however, the precise function remains unknown. ACBP is expressed at relatively high levels in the epidermis, particularly in the suprabasal layers, which are highly active in lipid synthesis. Targeted disruption of the ACBP gene in mice leads to a pronounced skin and fur phenotype, which includes tousled and greasy fur, development of alopecia and scaling of the skin with age. Furthermore, epidermal barrier function is compromised causing a ~50% increase in transepidermal water loss relative to that of wild type mice. Lipidomic analyses indicate that this is due to significantly reduced levels of non-esterified very long chain fatty acids in the stratum corneum of ACBP(-/-) mice. Here we review the current knowledge of ACBP with special focus on the function of ACBP in the epidermal barrier. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. Guest Editors: Kenneth R. Feingold and Peter Elias.