Granulocyte colony-stimulating factor (G-CSF) is a glycoprotein hormone which stimulates the proliferation and differentiation of a subset of granulocyte precursors and enhances some functional activities of mature neutrophils. We tested the effects of G-CSF on a patient with intractable infective endocarditis. The white blood cell count was increased 3-fold and the inflammatory reactions such as C-reactive protein and erythrocyte sedimentation rate were completely normalized without any side effects. This is the first report describing the use of G-CSF for infective endocarditis. Administration of G-CSF might be suitable for treating intractable infections which cannot be controlled by antibiotics alone.