Current treatment for Felty's syndrome, a triad of rheumatoid arthritis, splenomegaly and neutropenia, is often unsuccessful. Felty's syndrome may be related to decreased production of hematopoietic growth factors. We treated a patient with Felty's syndrome, profound neutropenia and a history of multiple complicated hospitalization for severe infections, with granulocyte colony stimulating factor (GCSF) for 18 months. After initiation of GCSF, the patient's neutrophil count has remained in the normal range for 18 months. After 2 easily treated infections at the start of therapy, she had only one episode of cellulitis occurring after 18 months when her GCSF dose was reduced to every 3rd day. She has been infection-free since then on every other day therapy. GCSF may be a cost effective longterm therapy for selected patients with Felty's syndrome and may reduce both patients' morbidity and overall medical costs.