Symptoms of Attention Deficit Hyperactive Disorder (ADHD) include hyperactivity, inattentiveness, and impulsivity, which are caused by dopamine dysfunction in the medial prefrontal cortex.  A six-hydroxydopamine lesion model of ADHD was used to examine response accuracy on an attentional task under one of three conditions: cue only, methylphenidate only (MPH), and MPH with cue.  Results indicated rats injected with methylphenidate and exposed to an external cue showed a significant increase in response accuracy compared to the MPH and cue only groups.  Also, the results indicate animals in the cue only condition had an increase performance in response accuracy compared to just methylphenidate group.  This study provides evidence that combination of a stimulant and external cue would have a stronger affect than a stimulant or external cue was given alone. Keywords: dopamine, hyperactivity, methylphenidate, external cue, medial prefrontal cortex