The purpose of this study was to compare components of the rat and human auditory event-related potential (ERP) as generated in active oddball and passive single-stimulus tasks. The rats were trained to discriminate between target and standard stimuli in an oddball task, whereas the human subjects received instructions. Task effects on various ERP components were found in both species. Interestingly, effects on the P3 component were similar in the species with regard to amplitude: Target stimuli elicited a higher amplitude in the oddball task than did standard stimuli. This might indicate that the P3 shares the same characteristics between species. However, the first four components occurred 1.82 times earlier in rats than in humans, expecting a P3 of about 200 ms in rats. The P3 in rats appeared at 380 ms. We conclude that either the relation between human and rat peak latencies is not linear, or the P3 in rats is not the equivalent of the human P3.