The vascular relaxant effects on isolated rat aorta of amlodipine camsylates (S-, R-enantiomer, and R/S-racemate), were evaluated and compared with that of S-amlodipine besylate. Furthermore, antihypertensive effects were measured in spontaneously hypertensive rat (SHR). The S-amlodipine camsylate concentration-dependently inhibited $Ca^{2+}$-induced contraction of rat aorta with a very slow onset of action (reached its maximum at 3.5h; $ED_{50}:;1.50;{pm};0.24$ nM), having a potency 2-fold higher than those of R/S-amlodipine camsylate $(ED_{50}:;3.36;{pm};0.91;nM)$ and similar to those of S-amlodipine besylate $(ED_{50}:;1.44;{pm};0.14;nM)$, whereas the R-amlodipine camsylate has 590-fold lower vasorelaxant activity $(ED_{50}:;886.4;{pm};49.7;nM)$. In SHR, orally administered S-amlodipine camsylate produced a dose-dependent and long-lasting (>>10 h) antihypertensive effect $(ED_{20}:;0.89;mg/kg)$, with a potency 2-fold higher than those of R/S-amlodipine camsylate $(ED_{20}:;1.82;mg/kg)$ and similar to those of S-amlodipine besylate $(ED_{20}:;0.71;mg/kg)$. In contrast, the R-amlodipine camsylate has no effect even-though administrated high concentration 10 mg/kg. These results suggest that S-amlodipine camsylate has the potency and long-lasting antihypertensive activity as single enantiomer drug, and its antihypertensive effect is not significantly different to that of S-amlodipine besylate.