To investigate how Ca²⁺ regulates airway ciliary activity, changes in ciliary beat frequency (CBF) and intracellular calcium concentration ([Ca²⁺]_i) of rabbit tracheal ciliated cells, in response to ATP, were simultaneously quantified with high‐speed phase‐contrast and fast fluorescence imaging. [ATP]⩽ 1 μm induced an increase in [Ca²⁺]_i and CBF that declined to the initial basal levels and was followed by irregular brief increases in [Ca²⁺]_i and CBF. [ATP] > 1 but < 16 μm induced a similar increase in [Ca²⁺]_i and CBF but this was followed by oscillations in CBF and [Ca²⁺]_i. The minimum CBF of the oscillations in CBF remained elevated above the basal rate while the minimum concentration of the [Ca²⁺]_i oscillations returned to the basal level. The minimum and maximum CBF of the oscillations in CBF were independent of the [ATP], whereas the frequency of the oscillations in CBF was dependent on the [ATP]. Similar oscillations in CBF and [Ca²⁺]_i were induced by ATP‐ γ ‐S. Although ADP, AMP and adenosine induced a Ca²⁺‐independent increase in CBF, neither ATP nor ATP‐ γ ‐S induced an increase in CBF when the Ca²⁺ increases were abolished by 20 μm BAPTA AM, a result suggesting that ATP hydrolysis was minimal. [ATP]≥16 μm induced a sustained elevation in CBF and only a temporary, non‐oscillating increase in [Ca²⁺]_i. A similar response was induced by thapsigargin (2 μm). Flash photolysis of caged Ca²⁺ (NP‐EGTA) produced both transient and prolonged increases in [Ca²⁺]_i which were accompanied by transient and sustained increases in CBF, respectively. From these results, we propose that CBF can be increased by a direct Ca²⁺ ‐dependent mechanism that generates the rapid increases in CBF associated with the oscillations or by an indirect Ca²⁺‐dependent mechanism that is responsible for the sustained minimum increase in CBF.