For some time I have thought that patients with tumors of the brain have a blood pressure that is perhaps lower than is usually found in a person of that particular age, so much so, in fact, that in my studies of patients who present themselves showing evidence of chronic cerebral impairment I have come to be biased against the diagnosis of tumor of the brain in the presence of arterial hypertension. In order to determine whether I am justified in this attitude of bias against the diagnosis of tumor in patients with arterial hypertension this review has been undertaken and 100 cases from my files of verified tumors of the brain have been studied. No effort has been made to select the cases; they are consecutive cases, except that two groups have not been included in the study. The two groups omitted are the pituitary tumors and those in