The protein encoded by this gene is a bifunctional enzyme and is one of the four enzymes of the peroxisomal beta-oxidation pathway. The N-terminal region of the encoded protein contains enoyl-CoA hydratase activity while the C-terminal region contains 3-hydroxyacyl-CoA dehydrogenase activity. Defects in this gene are a cause of peroxisomal disorders such as Zellweger syndrome. Two transcript variants encoding different isoforms have been found for this gene.