This investigation was performed to study the effect of Ginseng water extract on the cardiac sarcolemma $Na^+,;K^+-ATPase$ activity of rat hearts. The Ginseng water extract (100mg/kg/day) was administered orally to Sprague-Dawley rats for one, four and seven days. The fragment of sarcolemma was prepared by the method of Matsui and Erdmann and the $Na^+,;K^+-ATPase$ and $Mg^{++}-ATPase$ activity were measured by the method of Martins and Doty. $Na^+,;K^+-ATPase$ activity in the rat heart treated with Ginseng water extract for 1 day was not significantly different from control value, but the activity was decreased by 13.4% in the rat heart treated for 4 days and was decreased by 20.4% in the 7 days treated group. $Mg^{++}-ATPase$ activity in the rat treated with ginseng water extract was similar to control value. It may be concluded that chronic administration of Ginseng may inhibit the $Na^+,;K^+-ATPase$ enzyme activity, but single administration may not inhibit the activity.