Prefrontal dopamine is catabolized by the catechol-O-methyltransferase (COMT) enzyme. Current evidence suggests that the val/met single nucleotide polymorphism in the COMT gene can predict the efficiency of executive cognition in humans. Individuals carrying the val allele perform more poorly because less synaptic dopamine is available. We investigated the influence of the COMT polymorphism on motor performance in a task that requires different executive functions. We administered a manual aiming motor task that was performed under four different conditions of execution (prepotent control condition, inhibitory control condition, distractor condition and higher index of difficult condition) by 111 healthy participants. Participants were grouped according to genotype (met/met, met/val, val/val), and the motor performance among groups was compared. Overall, the results indicate that met/met carriers presented lower levels of peak velocity during the movement trajectory than the val carriers, but met/met carriers displayed higher accuracy than the val carriers. It is possible that the met/met allele carriers executed more controlled movements and thereby generated a lower magnitude of peak force (peak velocity) during the trajectories. The main objective of this more controlled processing was to guarantee accuracy to the movement endpoint. Interestingly, the better spatial accuracy exhibited by the met/met allele carriers was not observed under the higher index of difficulty condition. This result shows that the association between the COMT polymorphism and motor control depends on the sensory-motor aspects of the task. This study found a significant association between the COMT polymorphism and manual aiming control. Few studies have investigated the genetics of motor control, and these findings indicate that individual differences in motor control require further investigation using genetic studies.