Aim: To raise awareness about the existence of excitated delirium syndrome in a psychotic patient with fever. Case report: A 32-year-old patient was forcibly hospitalized five times in the last 11 years at the Clinic for Psychiatry at the University Hospital Center Rijeka. For the past 14 years, he has undergone sychiatric treatment with the diagnosis of paranoid schizophrenia, and the excitatory delirium syndrome occurred three years after the beginning of the treatment. In the last two involuntary hospitalizations, the patient was presented with a clinical picture of psychosis and impaired consciousness (delirious by description), psychomotor agitation, non-cooperation with symptoms of autonomic hyperreactivity (tachycardia, tachypnea, sweating, increased blood pressure) muscle rigidity. In addition, the patient had a constant need for undressing and a pronounced attraction to mirrors. On the third day of the last hospitalization, there was elevated body temperature which coincided with the administration of a higher dose of antipsychotics. Malignant neuroleptic syndrome was first suspected and antipsychotic therapy was discontinued, but without a significant effect on mental and physical condition. Diagnostic processing did not show a significant increase in creatine phosphokinase levels or the finding of myoglobin in the urine. Taking this into account, antipsychotics were reintroduced in the treatment, and the mental and physical condition of the patient gradually improved, and then a unique excited delirium syndrome was suspected. Conclusion: The occurrence of fever in psychiatric patients is diagnostically and therapeutically challenging. Early consideration of treatment-related hyperthermia syndromes is vital. The diagnostic dilemma between malignant neuroleptic syndrome and excitatory delirium syndrome is significant because different therapeutic approaches are involved, and these are two potentially lethal syndromes.