Associating natural rewards with predictive environmental cues is crucial for survival. Dopaminergic (DA) neurons of the Ventral Tegmental Area (VTA) are thought to play a crucial role in this process by encoding reward prediction errors that have been hypothesized to play a role in associative learning. However, it is unclear whether this signal is still necessary after animals have acquired a cue-reward association. In order to investigate this we have trained mice to learn a Pavlovian cue-reward association. After learning, mice show robust anticipatory and consummatory licking behavior. As expected calcium activity of VTA DA neurons goes up for cue presentation as well as reward delivery. Optogenetic inhibition during the moment of reward delivery disrupts learned behavior, even in the continued presence of reward. This effect is more pronounced over trials and persists on the next training day. Moreover, outside of the task licking behavior and locomotion are unaffected. Similarly to inhibitions durin...