We report the case of a 48-year-old man with adult-onset adrenoleukodystrophy (ALD) who developed dementia with subacute onset. He was abulic, indifferent to his surroundings, and without insight with regards to his own disease. An elevated plasma very long chain fatty acid level and a novel point mutation IVS3+2t>g in the ABCD1 gene confirmed the diagnosis of ALD. Diffusion-weighted MRI revealed a high intensity area in the white matter of the frontal lobes. Severe brain hypoperfusion in the frontal lobes was revealed. We believe that this is a rare case of adult-onset adrenoleukodystrophy with predominant frontal lobe dysfunction.