Many polymorphisms have been described for the genes encoding the beta 1, beta 2, and alpha 2c-adrenoceptors that result in altered signaling and/or regulatory properties of the receptors. Several studies have investigated whether these properties affect the cardiovascular function of these receptors in mice or in humans, but have yielded mixed results. Some studies suggest that adrenoceptor polymorphisms might alter the risk for heart failure and the response to treatment with beta-blockers. However, the complex haplotypes resulting from combinations of individual polymorphisms have not yet been investigated, and firm conclusions or recommendations cannot be made because of the low patient numbers in each of the study programs.