Dopaminergic agonists and antagonists were tested on the field-stimulated mouse vas deferens. Both LY 171555 and SK & F 38393, relatively selective DA2 and DA1 receptor agonists, respectively, produced concentration-dependent inhibition of the field stimulation-induced contractions, without modifying the baseline tone nor the contractile responses to the exogenous noradrenaline. Both LY 171555 and SK & F 38393 concentration-response curves were shifted rightward in a parallel manner by sulpiride (relatively specific DA2 antagonist) and SCH 23390 (relatively specific DA1 antagonist), respectively. The results are suggestive of the existence of pre-junctional dopamine receptors involved in the regulation of sympathetic neurotransmission in rodent vasa.