This study was based on a method of microphotometrical measurement of the ciliary beat of cells from the human upper respiratory tract. The ciliated cells were acquired by the tissue cultivation of small pieces of nasal mucosa obtained during surgical interventions in the paranasal sinuses. The experiments were performed in a chamber where the cells were superfused by a tyrode solution. The ciliary beat was measured by a microscope photometer built into an inverted microscope. During the measurements the diaphragm aperture of the photometer was positioned over the cilia in such a manner that the changes of light intensity resulting from the movement of the cilia could be registered. The frequency of the ciliary beat was estimated by counting the individual beats. The ciliary beat during control conditions was studied as well as the influence of temperature. Cooling of the experimental chamber resulted in a significant reduction of the frequency of the ciliary beat. The advantages of this single cell preparation of ciliated epithelia for pharmacological investigations are discussed.