Although there is a relatively high prevalence of both idiopathic Parkinson's disease (PD) and epilepsy in the elderly population, and PD occurs more frequently in people with epilepsy, there are no studies investigating the efficacy and tolerability of antiepileptic drugs (AEDs) in people with PD. We describe the case of a 71-year-old man with PD who experienced several seizures. The initiation of antiepileptic treatment with oxcarbazepine (OXC) provoked a severe, long-lasting psychotic state. The patient had previously experienced similar psychotic episodes during dopamine agonist therapy. Because recent animal studies have proven that OXC and its active metabolite exert important dopamine- and serotonin-promoting effects in the limbic area, we assumed that in our case the OXC-induced psychosis was mediated by the dopaminergic system. We concluded that OXC should be used with care in cases of a constellation of PD and epilepsy because of its possible psychiatric side effects. The dopaminergic effect of OXC and its active metabolite might also play an ambivalent, but important role in the treatment of alcohol addiction and bipolar disorder; therefore, further studies are required to investigate its psychopharmacological aspects.