Introduction: Frontotemporal dementia (FTD) is one of the leading causes of neurodegenerative dementia in people under 60 years old. Traumatic brain injury (TBI) is the most well-established environmental risk factor for dementia. Case Report: We present a case of 59-year-old male patient with 3 years history of behavioral abnormalities and personality changes with gradual onset. He had history of severe TBI about 20 years before the initial presentation, in which he needed a surgery for intracranial hemorrhage evacuation.The neuropsychological examination showed perseveration, impairment in executive function, verbal and visual memory and visuospatial. He was cooperative during examination but sometimes would show inappropriate and bizarre behavior toward the examiner. The MRI Brain result showed frontal and temporal atrophy. The patient was given symptomatic treatment, as there was no approved pharmacological therapy for FTD. Discussion: Behavioral changes are the presenting feature and dominate the clinical picture throughout the disease course. This patient was diagnosed with FTD because of the progressive abnormality of the behavior along with personality change. The imaging results showed lesions that caused by the TBI which happened almost 20 years before the initial symptom but also showed frontal and anterior temporal atrophy. In the absence of definitive biomarkers, the diagnosis of bvFTD is dependent on clinical diagnostic criteria. Conclusion: The present study emphasized the importance of a detailed history and neurological examination, including neuropsychological examination and brain imaging in the case of middle-aged patients with insidious onset of personality changes and behavior problems.