Glioblastoma multiforme is the most common primary adult brain tumor. Clinically, non-specific psychiatric symptoms may arise as their first and only manifestation, prior to any neurological deficits. The most form of psychiatric presentation of neurological diseases are depressive complaints, although these may also be accompanied by behavioral and/or cognitive, anxious and psychotic symptoms. By explaining this case report we aim to emphasize the importance of considering the diagnosis of an organic brain disease, even when only primary psychiatric symptoms are evident. The bibliographic research was made using PubMed and Scielo, and analysis of the electronic patient process. Man of 68 years with a history of hypertension, nephrectomy, splenectomy and left brachial plegia after a car accident. He had been previously seen by a psychiatrist for a 6-month history of depressive symptoms, which had been successfully treated. He later developed new behavioral changes such as heteroaggressiveness, social maladjustment and disfasia, for which he was sent to the emergency room. Brain-CT scan displayed a left front temporal expansive injury. Admitted to the Neurology Department for further diagnostic investigation. Subsequent MRI, detected massive infiltrative lesion with significant mass effect and cystic/necrotic area. The anatomopathology disclosed a glioblastoma grade IV. This case reinforces the importance of carrying a imagiologic workup in cases like this, especially on patients with atypical presentation of psychiatric symptoms.