In vitro nasal and tracheal ciliary beat frequencies (CBFs) were measured photometrically in brush samples of 15 patients undergoing bronchoscopy. Tracheal and nasal CBF values in these patients were found to be significantly correlated (r = .74, p less than .01), and the latter did not differ significantly from the nasal CBF of 80 subjects serving as controls. Premedication with morphine and atropine and local anesthesia with lidocaine hydrochloride significantly decreased the CBF. Among the control subjects, a significantly higher CBF (13.6 +/- 1.5 Hz) was found in the young age group (10 to 19 years) as compared to other groups (12.2 +/- 1.7 Hz). Gender and ethnic origin did not influence CBF in any age group. These data support the possible use of the in vitro study of nasal epithelium to reflect the CBF in the lower respiratory tract.