Ciliary motility and ultrastructure were studied in cystic fibrosis, bronchiectasis and Kartagener's syndrome and normal control subjects. In cilia from patients with Kartagener's syndrome, beat frequency was slower and there were more microtubular abnormalities and fewer dynein arms than for each of the other groups. In Kartagener's syndrome, ciliary motility and outer dynein arm numbers were positively correlated and there was a wide variation in each. Cystic fibrosis ciliary beat frequency and ultrastructure were normal.