A 40-year-old patient with long-standing Crohn's ileocolitis in remission experienced cyclic neutropenia with a periodicity of 14 days. He was not receiving immunosuppressive or myelosuppressive therapy. The patient had Staphylococcus aureus bacteremia resulting from central catheter infection, which was refractory to antibiotic therapy during the period of severe neutropenia. When granulocyte colony-stimulating factor (G-CSF) was administered, the cyclic neutropenia rapidly disappeared, the neutrophil and leukocyte counts normalized, and the sepsis resolved. When G-CSF therapy was discontinued, the leukocyte and absolute neutrophil counts again declined. With reinstitution of therapy, the leukocyte and absolute neutrophil counts recovered and normalized. Crohn's ileocolitis remained in remission during G-CSF therapy. This report confirms and extends one previous report of cyclic neutropenia associated with Crohn's disease and demonstrates in one patient the efficacy and safety of G-CSF on the hematologic, bacteriologic, and clinical manifestations of cyclic neutropenia associated with Crohn's disease.