Cytotoxic chemotherapy suppresses the hematopoietic system, impairing host protective mechanisms. One important consequence, chemotherapy-induced neutropenia (CIN), places patients at risk of developing fever and life-threatening infections. These complications have substantial economic impact and may severely affect the quality of life of patients undergoing treatment of cancer. Currently, CIN is managed by delaying and reducing chemotherapy treatment with hematopoietic growth factors and with intravenous antibiotic therapy. Reducing chemotherapy may compromise treatment outcomes in potentially curable malignancies, such as early stage breast cancer and non-Hodgkin's lymphoma. Randomized clinical trials have clearly shown that granulocyte colony-stimulating factor (filgrastim) and the longer-acting pegylated granulocyte colony-stimulating factor pegfilgrastim, when administered 24 hours after chemotherapy before the occurrence of CIN, are effective in reducing the incidence and severity of neutropenia and its complications, including administration of full doses of chemotherapy without treatment delay. Dose-dense chemotherapy, ie, the administration of standard-dose chemotherapy in shorter cycles (made feasible with growth factor support), has recently been shown to improve outcomes in early stage breast cancer and non-Hodgkin's lymphoma. This review summarizes the clinical consequences of CIN and describes current best practices for the management of patients at risk for CIN.