Many epilepsy patients, particularly those with complex partial seizures, also develop psychiatric disorders during the course of their illness and have to be treated with psychotropic drugs in addition to their antiepileptic medication. However, the brains of epileptic patients can be considered pathologically altered and psychotropic drugs may thus have profound and stronger effects on seizure threshold or unwanted side effects than in purely psychiatric patients. Thus, the knowledge of the mechanisms of psychotropic drugs is necessary to predict their effects in epilepsy patients. In this review, current concepts of the mechanisms of neuroleptic, antidepressant, and anxiolytic drugs emerging from basic and preclinical research are summarized, and the potential impact of using these drugs in epilepsy patients is discussed.