This study aimed at determining the pharmacological effects of three different Yahom extracts; Navaghougt, Intrarajak and Intara-osot (Prasatthong-osot); on cardiac function by using the isolated perfused rats' heart (Langenorff preparation). Three different Yahom extracts dissolved water at the concentration of 0.1, 0.5, 2.5, 12.5 and 62.5 microgram per milliliter were perfused into the heart throughout the experiment. Three different Yahom extracts increased heart contraction and heart rate, though the effects were not significant, showing that three different Yahom extracts possessed the cardiac stimulating effect both the positive inotropic and positive chronotropic effects. The mechanism of action of three different Yahom extracts seemed likely that involved the influx of calcium ion into the cardiac myocyte through the calcium ion channel since the cardiac stimulations were inhibited by verapamil, a calcium channel blocker. The effects of three different Yahom extracts were not through the stimulationof beta[subscript 1]-adrenergic receptor since the effects were not inhibited by propranolol, a nonselective beta[subscript 1] - blocker. The mechanism of three different Yahoms extracts might be similar to digoxin which inhibited the Na[superscript +]- K[superscript +] ATPase (sodium pump) since Yahom extract given with digoxin was not able to increased cardiac function more than that obtained from digoxin or Yahom extract alone.