Purpose: To clarify the effect of bradykinin on cytosolic free calcium mobilization and cell proliferation in cultured bovine corneal endothelial cells (BCEC). Methods: The cytosolic free calcium concentration (Ca<sup>2+</sup>]<sub>i</sub>) was measured with the InCa<sup>TM</sup> Imaging System after the treatment of bradykinin (10<sup>–11</sup> to 10<sup>–7</sup> M) alone or with the pretreatments of EGTA, bradykinin receptor (Bk<sub>1</sub> and Bk<sub>2</sub>) antagonists and an inhibition of phospholipase C (U-73122). Also, the effect of bradykinin on cell proliferation in BCEC was evaluated using cell counts. Results: In BCEC, [Ca<sup>2+</sup>]<sub>i</sub> in the resting state was 87 ± 9 n M. Bradykinin induced an increment of [Ca<sup>2+</sup>]<sub>i</sub> in a concentration-dependent manner and its 50% effective concentration was approximately 5 × 10<sup>–11</sup> M. A [Ca<sup>2+</sup>]<sub>i</sub> increment at 10<sup>–8</sup> M bradykinin was inhibited with the pretreatment of EGTA, an extracellular calcium chelator. U-73122 (5 × 10<sup>–6</sup> M) attenuated the bradykinin-induced [Ca<sup>2+</sup>]<sub>i</sub> increment. The pretreatment of HOE-140 (Bk<sub>2</sub> antagonist) almost attenuated the bradykinin (10<sup>–8</sup> M)-induced [Ca<sup>2+</sup>]<sub>i</sub> increase, but des-Arg<sup>9</sup>-[Leu<sup>8</sup>]-bradykinin (Bk<sub>1</sub> antagonist) did not suppress it. To investigate the physiological effect of bradykinin, the effect of bradykinin on cell proliferation was studied. 10<sup>–8</sup> M of bradykinin produced a significant increase in cell numbers. This mitogenic effect of bradykinin was inhibited by the Bk<sub>2</sub> antagonist. Conclusions: Bradykinin-induced stimulation of the signal transduction pathway in BCEC is coupled with the Bk<sub>2</sub> type receptor. Furthermore, bradykinin produces the mitogenic effect in BCEC.