A 58-year old sailor, few months after coming back from Laos, was hospitalized in University Hospital Center Sestre Milosrdnice, Department of Neurology. His wife noticed he was sleeping the whole time during last twenty days, had speech disorders, falls frequently, refuses food with progressive mental decline, involuntary jerks of left hand, weakness and balance disturbance. Extensive laboratories tests for autoimmune, hypercoagulable and paraneoplastic diseases were performed. All tests have been negative for possible infective diseases. Brain MRI with gadolinium showed chronic vascular lesions in white matter and changes in corpus callosum. PET/CT showed increased metabolism of FDG in the focus near right adrenal gland. Frequent myoclonus occurred, dominant at left side, and one grand mal seizure during hospitalization. Brain perfusion SPECT with 99m Tc HMPAO was performed and dominant right parietal and temporal hypoperfusion and hypoperfusion of left basal ganglia was found. Anti-NMDAR antibodies were positive in cerebrospinal fluid and in blood serum. Positive Anti-NMDAR antibodies in blood serum and CSL and PET/CT finding of tumor of right adrenal gland presumed the diagnosis of paraneoplastic anti-N- methyl-D-aspartate receptor encephalitis. Plasma exchange and intravenous immunoglobulins therapy was performed. Patient underwent extirpation of tumor that was confirmed patohistologically to be pheochromocytoma. Improvement in cognitive and verbal status is noticed. The brain perfusion SPECT is not the first choice in the diagnosis of anti-NMDA receptor encephalitis but is useful to objective the lateralization symptoms.