Epoxyeicosatrienoic acids (EETs), the cytochrome P450 epoxygenase metabolites of arachidonic acid, are potent vasodilators and are believed to be the endothelium-derived hyperpolarizing factor in a number of vascular beds. In addition, EETs may play a role in the secretion and action of insulin and the metabolism of carbohydrates and lipids. Pharmacological manipulation of EETs may be a useful therapeutic approach for disease states such as hypertension, diabetes mellitus and the metabolic syndrome. EET mimetics and antagonists and drugs that increase EET synthesis or decrease their degradation are currently under investigation. The cellular mechanism of action of EETs appears to be complex and is being intensively studied by a number of investigators. In the present article, EET production, metabolism, isomerism and vasodilatory effects will be reviewed and potential mechanisms of action discussed. The role of EETs in insulin secretion and sensitivity and their implication in diabetes mellitus and the metabolic syndrome will also be reviewed. Drugs affecting EET bioavailability and action may be promising agents to use to treat hypertension/insulin resistance. The effects of these agents in experimental vascular disorders will also be discussed.