The conditioned taste aversion (CTA) paradigm and microdialysis were used to determine if extracellular dopamine in the nucleus accumbens is related to the reward value of a stimulus. Intraorally applied saccharin caused a 37% increase in DA in naive rats and a 40% decrease in subjects with a CTA to this taste. These results suggest that accumbens DA is not just a function of arousal but is related to stimulus reward.