Adrenal chromaffin cells secrete catecholamine in response to acetylcholine. The secretory response has absolute requirement for extracellular calcium, indication that $Ca^{2+}$ influx through voltage dependent $Ca^{2+}$ channel (VDCC) is the primary trigger of the secretion cascade. Although the existence of various types of $Ca^{2+}$ channels has been explored using patch clamp technique in adrenal chromaffin cells, the contribution of different types of $Ca^{2+}$ channels to catecholamine secretion remains to be established. To investigate the quantative contribution of different types of $Ca^{2+}$ channels to cate-cholamine secretion, $Ca^{2+}$ current($I_{Ca}$) and the resultant membrane capacitance increment($Delta{C}_{m}$) were simultaneoulsy measured. Software based phasor detector technique was used to monitor $Delta{C}_{m}$. After blockade of L type VDCC with nicardipine (1$mu$M), $I_{ca}$ was blocked to 43.85$pm$6.72%(mean$pm$SEM) of control and the resultant ㅿC$_{m}$ was reduced ot 30.10$pm$16.44% of control. In the presence of nicardipine and $omega$-conotoxin in GVIA(l$mu$M), an N type VDCC antagonist, $I_{ca}$ was blocked to 11.62$pm$2.96% of control and the resultant $Delta{C}_{m}$ was reduced to 26.13$pm$8.25% of control. Finally, in the presence of L, N, and P type $Ca^{2pm}$ channel antagonists(nicardipine, $omega$-Conotoxin GVIA, and $omega$-agatoxin IVA, respectively), $I_{ca}$ and resultant $Delta{C}_{m}$ were almost completely blocked. From the observation of parallel effects of $Ca^{2+}$ channel antagonists on $I_{ca}$ and $Delta{C}_{m}$, it was concluded that L, N, and also P type $Ca^{2+}$ channels served and $Ca^{2+}$ source for exocytosis and no difference was observed in their efficiency to evoke exocytosis amost L, N, and P type $Ca^{2+}$ channels.