Summary:There is no brief patient-derived rating scale for staging and following profoundly demented Alzheimer disease (AD) patients. We developed the Baylor Profound Mental Status Examination (BPMSE) modeled after the Mini-Mental State Examination (MMSE) to meet this need. The BPMSE consists of 25 cognitive questions that assess orientation, language, attention, and motor functioning; 10 examiner ratings of presence or absence of problem behaviors; and 2 qualitative observations of language and social interaction. Two hundred eight probable or possible AD patients (MMSE scores of 20 or less) received the BPMSE. Some were also rated on the clinical dementia rating (CDR) and Lawton activities of daily living (ADL). A ceiling effect occurred at MMSE scores above 11. BPMSE cognitive scores and MMSE scores correlated significantly (r= 0.76,p< 0.0001). Subareas of the BPMSE also intercorrelated significantly. The BPMSE correlated with both CDR and ADL scores (p< 0.001). Internal consistency, interrater reliability, and test-retest stability were excellent. There was no floor effect, and BPMSE scores continued to decline after the MMSE reached 0. The BPMSE is a quick and easy staging tool with excellent validity and test-retest stability that measures cognitive function successfully in patients with MMSE scores below 12. The scale is sensitive to longitudinal change and continues to assess decline when performance has reached the lowest levels on conventional measures.