Frontal lobe lesions are associated with behavioral abnormalities and executive dysfunction. When these lesions occur early in life, the symptoms are even more severe as the anatomical and functional substrates underlying personality and behavior are damaged, distorting normal modulation by interaction with the psychosocial environment. We present a case of a 40-year-old man who suffered a frontal lobe lesion at the age of nine years and developed impulsivity, disinhibition and inappropriate behaviors while showing some preservation of insight. Brain MRI revealed lesions to bilateral orbitofrontal cortex, ventromedial prefrontal cortex, anterior cingulate gyri and genu of the corpus callosum, which were more extensive on the right side. The right prefrontal dorsolateral cortex was severely damaged, whereas the right ventrolateral prefrontal cortex was spared. We will discuss the correlation of the damaged pre frontal regions with the symptoms presented by the patient.