The purpose of this study was to investigate the effectiveness of mental practice in increasing accuracy of performance during motor task. Forty healthy students aged 17 years were randomly assigned to two groups. The experimental group(n=20) performed mental practice; the control group(n=20) performed nothing. The task was dotting. No significant change was seen between pre and post test subtest results following mental practice sessions(p>0.05). The experimental group's accuracy improved a little but this was not valuable statistically(p>0.05). We could not prove that mental practice was effective in increasing accuracy of motor task performance.