Alzheimer disease (AD) has become a real catastrophe for elderly persons and the leading attention of geriatricians in the world as well as in Vietnam. In diagnostic domain, beside clinical diagnosis, gene and biomolecular diagnosis, new medical imaging methods including MRI playing an important role in diagnostic assistance, helping differentiating diagnosis and surveillance of AD. Purposes: Initial studying of clinical and MRI aspects of Alzheimer patients in the National Hospital of Gerontology. Objects and research method: 26 patients with AD diagnosis determined by clinical criteria, received brain MRI in the National Hospital of Gerontology . for AD differenciating diagnostic assistance and definite diagnosis from 2/2008 to March 2010. Results: 1- Alzheimer disease happens frequently in old persons over 60 years old (88.6 percent), especially over 70 years old (65.4 percent). Risk factors of AD including high age, female sex (Female:Male=2.7:1), lowly scholarly, popular labour, hyperlipidemia disorders and less participation to socilal activities. Clinical manifestation is slowly but evolutively memory loss, simply or complicatedly with other cognitive disorders. 86.4 percent AD patients coming to hospital in moderate and severe stages with mean MMSE only 13.42. 2- MRI aspects in AD patients: 100 percent AD patients having diffuse and systematic or more focal regional brain atrophy. Frontal atrophy seen in 100 percent patients, successively temporal regions (in 69.2 percent AD patients) and parietal regions (in 65.4 percent). Occipital atrophy is less common with 19.2 percent and present in severe stage. Hippocampal atrophy (92.3 percent) and atrophy of corpus callosum (88.5 percent) are quite frequent signs. Evan index is higher than normal in 57.7 percent, the higher the Evan index is, the lower marks of neuro-mental tests are, and then the worse the patient's demential condition is. Conclusion: MRI is a safe and non-invasive medical imaging method, having an important role in diagnostic assistance of Alzheimer disease associated with clinical and biochemical criteria. MRI can be used to differentiate diagnosis and follow up the evolution and then prognosis of AD.