Mechanical stimulation of the cell surface or cilia of cultured ciliated epithelial cells derived from the rabbit tracheal mucosa resulted in a transitory ciliary beat frequency increase of 20% or more. This response was composed of a lag, rise, and recovery phase. The duration of the response, but not the maximal frequency, was increased by stronger stimulation. The ability of these ciliated cells to respond to stimulation depended on culture age; generally, cultures younger than 4 days were insensitive. The frequency response was transmitted to adjacent and more distal cells in all directions. The lag phase but not the rise time of the adjacent cell response was extended. These ciliary responses were lost when extracellular Ca2+ was removed. Replacement of Ca2+ resulted in a restoration of mechanosensitivity. In 1 mM verapamil and Ca2+ the frequency response was also lost. These results suggest that the frequency response is dependent on Ca2+ influx (although its intracellular action is unknown) and imply that mucociliary clearance is a localized self-regulating process.