Chronic wounds are associated with considerable morbidity and prolonged hospitalizations. The availability of recombinant growth factors and cytokines provides a new modality for treatment of recalcitrant wounds. Granulocyte-macrophage colony-stimulating factor (GM-CSF), a growth protein for hematopietic cells, also enhances neutrophil and monocyte function and promotes keratinocyte proliferation. In three patients with inherited disorders associated with leukocyte dysfunction and non-healing wounds, topical application of GM-CSF resulted in complete wound closure within 1 to 4 weeks. A subcutaneous (s.c.) infusion pump for the local s.c. delivery of GM-CSF was also found to enhance healing. Local application of GM-CSF may thus promote wound closure in patients with impaired wound healing.