Granulocyte-macrophage colony-stimulating factor (GM-CSF) has been used extensively to restore hematopoietic system function after damage by diseases such as myelodysplastic syndrome or by cytotoxic anti-cancer agents used during cancer chemotherapy or prior to bone marrow transplantation. The clinical benefits of this approach have included fewer infections, fewer hospital days and less antibiotic use. In the future, the use of GM-CSF will be focused on special situations within these general areas, plus new directions that were not previously given sufficient attention. Examples of focused approaches include the use of GM-CSF in the control of fungal or protozoal disease and to take advantage of anti-tumor effects of myeloid cell activation. The anti-microbial effects will also be explored in patients who are not neutropenic but have serious infections which may be benefited by increased stimulation to myeloid cell function. The use will also be focused on mobilization of peripheral blood progenitor cells and in cycling of normal hematopoietic and malignant cells. The new directions will include use of GM-CSF by local application in healing of cutaneous ulcers, rapid wound closure and skin grafting. Because of its potent effects on immunologic mechanisms of antigen presentation, it will be used in several ways as a vaccine adjuvant. This adjuvant action will be directed at enhancing immunologic responses to antimicrobial antigens and anti-tumor antigens. The future of GM-CSF as a tool for hematopoietic and immunologic stimulation with resulting important clinical benefits is clear.