Abstract: The present invention provides a method of treating Alzheimer's disease, which method comprises administering to a person requiring such treatment, a pharmaceutically acceptable acid addition salt of deferoxamine USAN. Such salts are preferably administered parenterally in the form of aqueous solutions. The dosage of suitable acid addition salts of deferoxamine, e.g. of the mesylate, is conveniently from about 0.2 to 5 g daily, preferably from about 0.2 to 1.5 g and in particular about 0.5 to about 1.0 g daily, especially twice daily 0.5 g, depending on the individual condition of the patient and the stage of the disease.