Lithium (as lithium carbonate) is an unexpensive drug, widely used in psychiatry for over 50 years in treatment of mood instability (bipolar disorder) and as an adjunct to antidepressants. Hematological effects of neutrophilia and increased circulating CD34⁺ cells of marrow origin have long been known. Lithium was at the center of hematological investigations in the 1980s, but no definitive use in hematology has yet emerged. We review evidence that lithium increases G-CSF and augments G-CSF effects. We suggest possible therapeutic uses of lithium in neutropenia. In bone marrow transplantation, preharvest lithium-assisted hematopoietic stem cell mobilization may be useful as well.