Male rats were anesthetized with chloral hydrate, and extracellular dopamine concentrations in the nucleus accumbens were measured using high speed chronoamperometry. Recordings were obtained during application of air passed through bedding obtained from cages that housed estrus female rats and application of depolarizing concentrations of potassium (K+) to the accessory olfactory system. Application of bedding-impregnated air increased the electrochemical signal obtained from within the nucleus accumbens, and this response was enhanced by treatment with the DA re-uptake blocker, GBR-12909. Application of K+ to the vomeronasal nerve layer of the accessory olfactory bulb and to the accessory olfactory bulb, itself, also elicited increases in the electrochemical signal recorded from the nucleus accumbens. These results indicate that the accessory olfactory system is able to activate the mesolimbic DA system.