CNS-level changes caused by chlorpromazine and clothiapine, a structural analogue, were studied with a battery of behavioral tests in rats, along with the ability of these two drugs to antagonize electrically and alpha-stimulator (phenylephrine-)induced contractions in the rat vas deferens. The findings indicated that clothiapine, while less effective as an alpha-receptor antagonist, was a much more active CNS-depressant than chlorpromazine.