AbstractThe possible calcium antagonistic action of the anti‐anginal drug terodiline was investigated by two experimental techniques. In isolated preparations of rabbit aorta and pregnant human uterus exposed to a calcium‐free medium and then depolarized by potassium, terodiline in concentrations of 4.5–36 μM inhibited contractions produced by cumulative addition of calcium to the extracellular medium. This effect of terodiline could be reversed by high concentrations of calcium. Within the same concentration range, terodiline also reduced potassium‐induced45Ca influx in isolated aorta without affecting calcium efflux. It is suggested that terodiline, which structurally has similarities to prenylamine and fendiline, like these drugs can be classified as a calcium an