text: The potency of the antipsychotic drug, << risperidone >>, to antagonize [[ alpha 1A-adrenoceptor ]]-mediated contraction in rat vas deferens and vasoconstriction in rat perfused kidney, and alpha 1B-adrenoceptor-mediated contractions in spleen from guinea-pig and mouse was evaluated and compared to that of alpha 1-adrenoceptor subtype-discriminating antagonists.