The cause of cystic fibrosis has been determined to be faulty ionic transport of chloride across the apical membrane of epithelial cells lining exocrine glands. The subnormal ionic transport leads to dehydration of extra cellular fluids and the development of thickened inspissated mucous secretions. The vast majority of patients with cystic fibrosis develop sinus disease with panopacification of the sinuses present in 90% to 100% of patients older than 8 months of age. Indications for surgical management of sinusitis in children with cystic fibrosis include (1) chronic nasal obstruction with mouth breathing, (2) chronic purulent draining nasal secretions unresponsive to medical treatment, and (3) persistent headaches thought to be related to sinusitis. Operative therapy is based on computerized tomographic scan findings and can be performed endoscopically. Postoperative management is critical for ensuring successful surgical results. Antibiotics, topical steroids, and cleansing of the surgical fields must be performed on a regular basis to ensure adequate healing. The impact of sinusitis on the cystic fibrosis population is significant. Approximately 20% of patients will eventually require surgical treatment of their sinuses. Chronic sinusitis may cause deformities of the external nasal skeleton, a loss of the sense of smell, and headaches.