Neuroleptic Malignant Syndrome (NMS) is a rare but potentially fatal neurological complication of medications affecting the central dopaminergic system, especially antipsychotic agents. According to one theory, decreased dopamine activity in the central nervous system plays a role in the pathogenesis of NMS. Clinically, patients exhibit resistant fever, neurological and autonomic findings, and laboratory changes. In this article, we aimed to present a case of neuroleptic malignant syndrome due to a single dose of venlafaxine, which presented with hyponatremia and high fever.