Abstract: The influences of several extracts from sinocalamus affinis on Ca²⁺ influx and efflux in the isolated aortas and hearts of rats were investigated by using ⁴⁵Ca as a radioactive tracer, and the calcium antagonistic effects were evaluated. The results indicate that the alkali extracts of sinocalamus affinis have a prominent influence on Ca²⁺influx and efflux in the isolated rat aorta and heart, in which they can markedly block ⁴⁵Ca entering into cell and can stimulate efflux of intracellular superfluous Ca²⁺. Moreover, the dose effect relation of calcium antagonistic effects is obvious. However, it is very difficult to conclude that whether the flavonoid and saccharide in sinocalamus affinis are involved in the calcium antagonistic effects and Ca²⁺ channels or not, just based on the results until now.