A series of 2-(aminomethyl)imidazolines related to the alpha-adrenergic antagonist phentolamine was prepared and evaluated for alpha-adrenergic agonist and antagonist activities in the isolated, field-stimulated rat vas deferens. Affinities for alpha-adrenergic receptors were determined by displacement of [3H]clonidine and [3H]prazosin from membrane binding sites of calf cerebral cortex. This series provided a variety of alpha-adrenergic profiles, with some of the (aminomethyl)imidazolines being nonselective alpha 1- and alpha 2-adrenergic antagonists like phentolamine, while others were either nonselective alpha 1- and alpha 2-agonists or mixed alpha 1-agonists/alpha 2-antagonists.