Abstract: Following a preliminary investigation on the cadiotonic effect of tupistrin, a glycoside isolated from the roots of Tupistra fimbriata H-M., the cumulative effect, speed of onset of action, and therapeutic coefficient of this glycoside were studied. Tupistrin was shown to have a rapid on et of action. In pigeons receiving a dose of 0.5 MLD/kg, Tupistrin could no longer be detected 24 hours later. Tupistrin was shown to give less cumulative effect than k-strophanthin. Using the guinea pig method, the authors found that the therapeutic coefficient of tupistrin was 3.32, while that of g-strophanrhin was 2.31. Tupistrin showed no haemolytic effect in test using human, rabbit or guinea pig blood. The solution of tupistrin was stable on autoclaving.