It was previously reported that the deterioration rate of contractile force of the isolated heart from ginseng extract treated rat was slower than that from control. Present study was carried out to investigate the mechanism of the action of ginseng on the contractile force of the papillary muscle in terms of calcium metabolism. Rats weighing 200-300g were administered orally with ginseng ethanol extract (100mg/kg/day) for more than 10 days. The isolated papillary muscles from rat hearts were suspended in bath containing Krebs-Henseleit solution. When equilibration of contractile force of papillary muscle was reached, the rates of deterioration of contractile forces of papillary muscle from ginseng component treated rats were determined by washing with Ca-free Krebs-Henseleit solution and compared with that of normal hearts. At the beginning of washing, the rate of deterioration of contractile force of the papillary muscle was slower significantly in ginseng treated rats than in control rats, suggesting that calcium may be somehow involved in sustaining the contractility in ginseng treated hearts. Anoxia of papillary muscle with nitrogen gas to muscles inhibited the contractility, but differences between control and ginseng treated groups in the rate of deterioration were not observed. Influence of diltiazem, calcium blocker, on the contractility of papillary muscle from ginseng treated and control hearts was studied. Contractility of papillary muscle from control and ginseng treated hearts was inhibited by diltiazem in dose dependent manner but the inhibition of the ginseng treated muscles was much weak. The effect was significantly different. From the results, it seemed that slowing in deterioration rate of papillary muscle from ginseng treated hearts might be related to calcium which was mobilized from plasma membrane of internal organelle by ginseng.