Angiotensin II (AII) induces an initial rapid but transient rise in [Ca 2+] i detected with aequorin in bovine adrenal capsule strips. The rise in [Ca 2+] i begins immediately after AII addition, reaches a peak in 30 seconds, and returns to near basal values within 5 minutes. The [Ca 2+] i transient is receptor-mediated and its height is dose-dependent. The increase in [Ca 2+] i is largely due to the release of Ca 2+ from an intracellular pool. The uncorrected peak rise in [Ca 2+] i after 1×10 −6M β-[asp 1]-AII stimulation is approximately 3 fold, from 110nM to 300nM; the peak rise, corrected for diffusion and nonsynchronous cellular response, is from 110nM to 1.2μM. Perifusion of aequorin-loaded strips with π-[asp 1]-AII, an aminopeptidase-resistant analog of AII, allows the simultaneous measurement of [Ca 2+] i and aldosterone production rate. Levels of agonist which generate a transient rise in [Ca 2+] i also produce a sustained increase in aldosterone production rate, but the two events are temporally separated: the transient rise in [Ca 2+] i precedes the increase in aldosterone production rate. However, there is a strong correlation, r=0.94, between the amplitude of the initial [Ca 2+] i transient and the magnitude of the sustained increase in steroid production rate.