Effective interpersonal interactions necessitate constant monitoring of others’ actions, a process known as interpersonal performance monitoring, which is influenced by the dopaminergic system and characterized by specific electrocortical signatures. To examine how this process is affected in Parkinson’s Disease (PD), we assess patients with PD performing coordination tasks with a virtual partner (VP) under two conditions: on dopaminergic medication (PD ON) and after withdrawal (PD OFF). During Interactive trials, which require adaptation to the VP’s actions, PD OFF performance is impaired compared to PD ON. Electroencephalography (EEG) analysis reveals in PD OFF increased midfrontal Delta-Theta activity during Interactive trials. Multivariate EEG analysis distinguishes Interactive from Cued trials, especially in PD OFF. Our findings highlight the role of dopamine in modulating electrocortical markers of interpersonal performance monitoring, with significant implications for understanding and treating PD.