The chest X-ray film of a girl with cystic fibrosis (CF) showed slowly increasing mottled densities during the 6th and 7th year of her life. Pulmonary symptoms and distress proceeded fast in spite of intensive treatment with antibiotics, corticosteroids, and physiotherapy. Three different fungal organisms were repeatedly cultured from the sputum: Candida albicans, Aspergillus fumigatus, and Exophiala dermatitidis. Antibodies against C. albicans were in the normal range. Candida antigen in blood and antibodies against A. fumigatus were absent. Antibodies against E. dermatitidis were detected by a recently developed indirect immunofluorescence assay. It seems most probable that E. dermatitidis was the causal agent for fungal pneumonia in this case. Under therapy with amphotericin B and flucytosine the clinical course and radiological appearance improved but definitive eradication of E. dermatitidis was only achieved after treatment with itraconazole. The isolation of this fungus from the sputum of a CF patient is reported for the first time. The significance of fungal infections in CF is discussed.