Twenty-six adult cystic fibrosis patients were studied to compare nasal disease with their laboratory correlates including skin testing, immunoglobulin and Aspergillus fumigatus precipitin levels, saccharin testing and sputum cultures. Six patients were asymptomatic and all of these had negative skin tests, normal IgE levels and negative Aspergillus fumigatus precipitins. Thirteen patients had rhinitis, 12 had positive skin-testing for common allergens, 10 elevated IgE levels and nine positive Aspergillus fumigatus precipitins. Seven patients had polyps, all had normal IgE levels and negative Aspergillus fumigatus precipitins, six had positive skin testing for common allergens. There also appeared to be a relationship between Pseudomonas spp. colonization and positive skin testing.