Over a 7-year period, three patients with cystic fibrosis had multiple sputum specimens that were smear- and culture-positive for Nocardia asteroides. Two of the patients had received long-term, low-dose inhalational corticosteroid therapy. Although all three patients were treated with cotrimoxazole, resulting in eradication of the organism from the sputum, there was no change in their clinical state, radiological findings, or pulmonary function. The isolation of Nocardia asteroides from the respiratory tract of cystic fibrosis patients is an unusual finding. Its presence does not necessarily imply disease, and in these three cases, it most likely represented colonisation. The clinical significance of Nocardia spp. isolated from the respiratory tract of cystic fibrosis patients needs to be considered in the context of the individual clinical picture.