A seventy-year-old woman was admitted to hospital with a Staphylococcus aureus respiratory tract infection. She had a history of extensive bronchiectasis and allergic bronchopulmonary aspergillosis (ABPA). Cystic fibrosis (CF) was suspected and cystic fibrosis transmembrane conductance regulator (CFTR) gene analysis showed F508del and R117H-7T mutations. In these mutations there is residual activity in the chloride channel in the cell membrane coded by the CFTR gene. This results in a much milder disease pattern varying from no disease at all to isolated organ disease. This type of disease is known as non-classical cystic fibrosis. In our patient the diagnosis of cystic fibrosis was made exceptionally late in life.