The auditory event-related potential was assessed in two experiments that evaluated the effects of stimulus factors on P300 (P3) component amplitude and latency. The first experiment manipulated the frequency of the target stimuli (500, 1,000, 1,500, and 2,000 Hz) and standard stimuli (250 and 4,000 Hz) in different conditions. Both P3 amplitude and latency were affected by the target and standard tone combinations in specific ways. The second experiment varied the target tone intensity and duration factorially. P3 amplitude was unaffected by these variables, but peak latency was significantly shorter for the loudest and longest target stimuli. The findings indicate that variation in auditory stimulus parameters can produce small but reliable effects for P3 values, which should be considered when results are compared across studies.