Extracting meaningful information from the positive and negative outcomes of actions is a key requirement for learning. To define the neural correlates of feedback processing, rapid event-related functional magnetic resonance imaging was used in an associative learning paradigm in normal human volunteers. Positive (compared with negative) feedback was associated with activations in the ventral striatum, midbrain and anterior and posterior cingulate cortex. No activations were seen for the comparison negative >positive feedback. Blood oxygenation level-dependent responses from the midbrain and the anterior cingulate cortex showed a phasic increase in response to positive feedback, whereas a decrease in response was seen for negative feedback. These results underscore the role of the reward system in feedback learning.