In a variety of smooth muscle cells, agonists induce a complex variation of the cytoplasmic calcium concentration ([Ca²⁺]_i-response). This response is composed of a series of cyclic increases in the ([Ca²⁺]_I, so-called Ca-oscillations, the pattern of which depends on both the type of tissue and the agonist considered. In tonic smooth muscle (e.g. airways, pulmonary artery…), Ca-oscillations are mainly dependent on a cyclic release of intracellularly stored calcium via an inositol trisphosphate (IP₃)-activated mechanism. The cyclic nature of Ca-release is in relation with the biphasic regulation of the IP₃-receptor located at the sarcoplasmic reticulum by the ([Ca²⁺]_I itself, on the one hand, and the functioning of sarcoplasmic reticulum Ca-pump, on the other hand. The role of Ca-oscillations in smooth muscle cell signaling is still a matter of debate. As a general rule, it is suggested that oscillations allow Ca²⁺ to function as a messenger while obviating the changes of sustained elevation of ([Ca²⁺]_i. Oscillations may also contribute to a frequency-dependent control of the smooth muscle cell response. Finally, Ca-oscillations participate to the control of the smooth muscle cell membrane potential value via the activation of Ca-dependent membrane ionic currents such as the oscillatory Cl^- current.