It has been suggested that ginseng can increase long-term resistance to stress and disease and therefore affect the lifespan. We set out to investigate this idea by testing whether the continuous administration of ginseng could affect the lifespan of mice and/or their behavioural responses to stress. 270 mice of strain LACa were divided into three groups: one group which was given ginseng from 8 weeks of age, a second group which was given ginseng from 52 weeks of age and an untreated control group. The mice were generally healthy. Their weights remained stable throughout their lifespan and were not altered by ginseng. Ginseng administration did not significantly alter the lifespan. However, ginseng did cause an exaggeration of the behavioural responses to mild stress. This effect was noticeable soon after ginseng administration and subsequently was maintained.