Chronic rhinosinusitis is extremely common in patients with cystic fibrosis. It causes numerous problems in these patients and can put them at risk for life-threatening illness. Potential problems include nasal obstruction, congestion, sinus pain and pressure, infection (usually with Pseudomonas organisms), hyposmia or anosmia, and the seeding of bacteria into the lower respiratory tract. Cystic fibrosis patients with chronically infected sinuses are at increased risk for pneumonia following lung transplantation. A prophylactic protocol has been developed for the management of chronic sinusitis in patients with cystic fibrosis. These patients are fully evaluated at the Nasal Dysfunction Clinic of the University of California, San Diego (UCSD), Medical Center. Based on the results of the evaluation, they are treated with endoscopic sinus surgery, partial middle turbinectomy, septoplasty, and a large middle meatal maxillary antrostomy. Surgery is followed by a rigorous regimen of pulsatile hypotonic saline nasal irrigation to wash away tenacious cystic secretions. Tobramycin (Nebcin) is given once daily in the nasal irrigant to inhibit the growth of Pseudomonas organisms. At the USCD Nasal Dysfunction Clinic, this prepulmonary transplantation protocol is now used in all cystic fibrosis patients with chronic sinusitis.