The effect of stimulant medication (methylphenidate) on the persistence of the maze-tracking performance of 24 hyperactive children was assessed in drug and placebo conditions using a double-blind design. There was no significant difference in errors (overshooting the maze boundaries) in the initial alleys of the maze. However, while on placebo, patients seemed unable to persist in their performance starting from the midpoint of the task through to its completion and made significantly more errors over this section of alleys in the unmedicated state than when on drug. These results suggest that while hyperactive children may be capable of giving adequate attention to a task in its beginning stages, they cannot sustain attention as the task progresses. Stimulant medication is effective in helping them to maintain their attention when it would otherwise begin to falter.