Pernicious anemia and its neurological complications, subacute combined degeneration of the spinal cord. Treatment of vitamin B12 deficiency states and macrocytic anemias associated with nutritional deficiencies, gastrectomy and abnormalities of, or malabsorption from, the gastrointestinal tract such as celiac disease, sprue and accompanying folic acid deficiency. Also suitable for use as the flushing dose in the schilling test for pernicious anemia.