In order to obtain derivatives with simultaneous alpha- and beta-adrenergic blocking activity, compounds having the phenoxypropanolaminic structure of beta-adrenergic blockers have been synthesised, as well as 1,2,4-oxadiazole moiety, which could imitate the imidazolinic nucleus characteristic of drugs acting on alpha-adrenergic receptors. The synthesised compounds have been submitted to alpha and beta receptor binding assays. Some derivatives showed an alpha-adrenoceptor binding activity higher than labetalol and similar to prazosin, but with a poor beta-adrenoceptor binding activity.