Alterations in personality accompany the onset and progression of dementia of the Alzheimer type. Longitudinal investigations of these changes using systematic quantifiable documentation have been infrequent. In this 3-year follow-up study, we report longitudinal observations of changes in personality in dementia of the Alzheimer type. Four response patterns were observed: (1) change at onset with little change as the disease continued, (2) ongoing change as the disorder progressed, (3) no change, and (4) regression of previously more disturbed behaviors. Repeated characterizations of the premorbid personality profile as determined by this inventory were found to be reliable.