Nebulized recombinant human DNase (rhDNase) reduces sputum viscosity, improves pulmonary function, and results in a small reduction in acute respiratory exacerbations requiring intravenous antibiotics in many patients with cystic fibrosis (CF). rhDNase is now recommended for use in CF patients with moderately severe suppurative lung disease. A 14-year-old girl with suppurative lung disease [forced expiratory volume in 1 second (FEV1) 69% and forced vital capacity (FVC) 81% predicted] secondary to Kartagener's syndrome and severe gastroesophageal reflux had worsening spirometry together with intractable gastrointestinal symptoms over the previous 18 months despite conventional treatment. She was, therefore, started on 2.5 mg rhDNase once daily. Her cough lessened and the volume of sputum decreased within 72 hours of commencement of treatment; this improvement was strongly associated with a dramatic reduction in gastrointestinal symptoms. Spirometry after 4 weeks of treatment demonstrated a 20% improvement in FEV1 and a 13% improvement in FVC. These improvements have been maintained after 4 months of rhDNase therapy. The use of rhDNase should be considered in patients with Kartagener's syndrome and a multicenter trial may be justified.