Recombinant human granulocyte colony-stimulating factor (G-CSF) has been used worldwide in cancer patients for over 1 year, and (only 5 years from the first publication on the clinical use of this growth factor) experience is rapidly accumulating in many oncological situations. Several randomized studies have confirmed its value in allowing the optimal delivery of chemotherapy without undue dose reductions or dose delays, while at the same time reducing the overall risks of febrile neutropenia associated with the use of cytotoxic chemotherapy. Its virtual lack of significant side effects, its selectivity of action, its rapid effect on neutrophil kinetics (reducing both the maturation and release times of bone marrow neutrophils to 1-2 days rather than the normal 4-5 days), and the reproducible augmentation of neutrophil production in several neoplastic and nonneoplastic situations, as well as the activation of myeloid cell functions, have made G-CSF the growth factor of choice in most cancer units. Some of the published information regarding its current and potential use in the management of oncological patients is summarized here.