Neuroleptic malignant syndrome (NMS) is a rare, but life-threatening, idiosyncratic reaction to neuroleptic medications that is characterized by fever, muscular rigidity, altered mental status, and autonomic dysfunction. NMS often occurs shortly after the initiation of neuroleptic treatment, or after dose increases. Malignant hyperthermia (MH) or malignant hyperpyrexia is a rare life-threatening condition that is usually triggered by exposure to certain drugs. The 46-years-old female patient was diagnosed schizophrenia at the age of 22. Currently, she is hospitalized due to psychotic decompensation. The patient was admitted with following daily dose therapy of: haloperidol 15 mg, biperiden 4 mg and diazepam 15 mg. During this hospitalization she developes muscle rigidity, tremor, hyperthermia, and laboratory results showed increase of enzimes CPK and LDH, so we started treatment of suspected malignant neuroleptic syndrome. After a treatment and recovery with complete withdrawal of all presented symptoms, our patient developed a malignant hypertermia that was resistant to all applicated medications. Our dilemma is whether presented symptoms of malignant hyperthermia are related to malignant neuroleptic syndrome or not?