To the Editor.— Pernicious anemia requires as its sine qua non the absence of intrinsic factor. Without demonstration of such a defect, either by Schilling test with and without exogenous intrinsic factor or, preferably, by direct assay for intrinsic factor, one can not be certain of the diagnosis. Wintrobe,1in listing causes of megaloblastic anemia, mentions 22 categories in addition to addisonian pernicious anemia. Indeed, it is probable that even in the United States the majority of patients with megaloblastic anemia do not have pernicious anemia (though it remains the most common cause of vitamin B12deficiency). The coexistence of neurological symptoms and gastric achlorhydria with megaloblastic anemia is very suggestive of the disease, but not diagnostic.1It is, for example, conceivable that alcoholic neuropathy, chronic gastritis with achlorhydria, and folic acid deficiency could be the presenting symptoms of a chronic alcoholic, though alcoholism was not a