This chapter analyzes the changes in the structure of intellectual activity in lesions of the frontal lobes. This group of patients are, characterized by the fact that the impairment can be easily compensated for, and normal intellectual activity restored by inhibiting impulsive answers and consolidating the orientation basis for intellectual activity. The chapter illustrates the authors' analysis of intellectual disorder, typical of this group of patients, by the review of a case where the symptoms of intellectual dysfunction gradually became increasingly more evident, as a result of the growth of an intracerebral tumor in the basal section of the frontal lobe. It presents the results of a study conducted a few days before the operation when the focal symptoms were aggravated by diffuse brain disorders, and then presents the findings of the study conducted with the same patient several months after the operation, when these additional impairments had disappeared.