Most of the current clinical treatments for Alzheimer's disease (AD) are largely symptomatic and can have serious side effects. We have tested the feasibility of using the granulocyte colony-stimulating factor (G-CSF), which is known to mobilize hematopoietic stem cells (HSCs) from the bone marrow into the peripheral blood, as a therapeutic agent for AD. Subcutaneous administration of G-CSF into two different beta-amyloid (Abeta)-induced AD mouse models substantially rescued their cognitive/memory functions. The rescue was accompanied by the accumulation of 5-bromo-2'deoxyuridine-positive HSCs, as well as local neurogenesis surrounding the Abeta aggregates. Furthermore, the level of acetylcholine in the brains of Tg2576 mice was considerably enhanced upon G-CSF treatment. We suggest that G-CSF, a drug already extensively used for treating chemotherapy-induced neutropenia, should be pursued as a novel, noninvasive therapeutic agent for the treatment of AD.