Many factors appear to be associated with intermittent focal cerebral arterial insufficiency. Most of them are added to atherosclerotic narrowing. For instance, systemic hypotension, polycythemia, alterations in the dynamic clotting mechanism of the blood, hypoglycemia, smoking, and other factors have been implicated at one time or another in the production of these episodes. If several factors are present, a cumulative effect may be noted. Recently we observed five patients who had attacks during a period of hypochromic anemia. All sought medical attention primarily because of these attacks. Although it is not possible to prove that the anemia is definitely related to the occurrence of episodes of intermittent focal cerebral arterial insufficiency, these cases seem of sufficient interest to be presented. Report of Some Cases CASE 1.—During the month prior to our first examination at the Mayo Clinic, a 50-year-old man had two 30-minute episodes of weakness in his left limbs.