To evaluate the impact of long-term granulocyte colony-stimulating factor (GCSF) treatment on quality of life of patients with congenital, cyclic, or idiopathic neutropenia. STUDY DESIGN, INTERVENTION, AND OUTCOME MEASURES: Twenty-one patients receiving daily subcutaneous GCSF responded to retrospective questions about disease-related symptoms and physical, psychological, and social functioning before and with GCSF therapy. Statistically significant improvement occurred in energy, emotional reactions, social isolation, functional ability, life satisfaction, decreased hospital admissions, and school attendance. GCSF greatly improves quality of life in patients with severe chronic neutropenia.