The influence of promised rewards on conflict resolution processes is not clearly defined in the literature, and the underlying mechanisms are poorly understood. Some studies have shown no effect of reward, while others have demonstrated a beneficial influence. In addition, although the basal ganglia are known to play a critical role in the association between motivation and cognition, the influence of promised rewards on conflict resolution processes in Parkinson's disease (PD) has received little attention. In this context, we assessed the influence of promised rewards on both impulse activation and suppression in 36 healthy participants and 36 patients with PD, using a rewarded Simon task. Analysis of performances revealed that promised rewards worsened the overall congruence effect, but only in healthy participants. Although the incentive context did not modulate the congruence effect in patients, by using the activation-suppression model, we were able to show that promised rewards did influence impulse suppression in patients-but not in healthy participants. Suppressing inappropriate response activation in an incentive context appears to be harder in medically treated Parkinson's disease. This indicates that incentive motivation can modulate at least one cognitive process involved in cognitive action control in patients with medically treated PD. The activation-suppression model provides essential additional information concerning the influence of promised rewards on conflict resolution processes in a pathological population