The most characteristic feature of airway inflammation in cystic fibrosis (CF) is the persistent infiltration of massive numbers of neutrophils. Although inflammation is primarily a protective response to injury, it has the potential to cause considerable harm when it is excessive. Recent recognition of the prominent role of inflammation has prompted the investigation of treatments designed to control inflammation in the CF lung. We report a 35-year-old man with abrupt stabilization of his rapidly progressive CF and forced expiratory volume (FEV1) after starting infliximab for his rheumatoid arthritis. This effect was sustained for 8 years while continuing to use twice-monthly infliximab.