A COMMON CONDITION: Vitamin B12 deficiency is common in the elderly. Search for deficiency should be undertaken whenever the clinical situation could lead to vitamin deficiency whether macrocytic anemia is present or not as its development may come late. PATHOPHYSIOLOGICAL IMPLICATIONS: The potential relationships between degenerative neuropsychiatric disorders and cerebrovascular or cardiovascular disease, mainly via hyperhomocysteinemia, emphasize the importance of searching for vitamin B12 deficiency in the elderly. SPECIFIC CAUSES: In the elderly, it is important to recognize specific causes of vitamin B12 deficiency, mainly resulting from vitamin malabsorption.