Ginseng saponins(GS), protopanaxadiol saponins(PD) and protopanaxatriol saponins (PT) were tested for the inhibition of the development of morphine tolerance and dependence antagonism of morphine analgesia and the loss of morphine tolerance and dependence in mice The results were as follows: 1. Inhibition of the development of morphine tolerance and dependence. 2. Antagonism of morphine analgesia. 3. Increase in the loss of morphine tolerance and dependence. Antagonism of morphine by ginseng saponins and its reversal by L-DOPA and 5-HTP suggest some possibility that catecholamines and serotonin levels might be associated with the results.