Granulocyte colony stimulating factor (G-CSF) stimulates the proliferation of neutrophils in bone marrow. In clinical practice, it can be used in febrile neutropenic patients to reduce the duration of febrile neutropenia and infectious events. In recent years, guidelines developed in Europe or U.S. recommended that prophylactic G-CSF should be used in patients who received the cheomotherapeutic regimen that show the risk of febrile neutropenia over 20%. However, in Korea prophylactic use of G-CSF is prohibited due to reimbursement problem.