A study was planned to see if the ginseng has any influence upon the weight of viscera of male and female rats. One hundred and ten male rats (body weight: 35 ~ 40 gm at the beginning of the experiment) and an equal number of females with similar body weight were use4 Excluding 10 male and 10 females which served as controls, these rats were divided equally into 4 groups (male ginseng group, male saline group, female ginseng group and female saline group), each of which comprising 50 animals. For 45 days, the male and female ginseng groups received every day 0.6 m1/100 gm body weight of ginseng extract solution (4 mg of ginseng alcohol extract in 1 ml of saline) subcutaneously, and the male and female saline groups received the same amount of physiological saline. Each group was further divided into 5 subgroups comprising 10 animals, and the 10 control rats and each subgroups were sacrificed immediately before, and 5, 15, 35, 35, and 45 days after beginning of the drug administration, respectively. The body weight of each subgroup was checked immediately before sacrificing it, and the heart, lung, liver, kidney, adrenal gland, spleen, and testis or uterus of each animal were weighed with a torsion balance. Following results were obtained: 1. Ginseng significantly facilitated gain in weight of testis and spleen as well as body weight of rats from 35th day after beginning of the drug administration on, but not before this time. 2. Ginseng did not exert significant influence upon the weight of heart, lung, liver, tidney, adrenal gland, and uterus of the rat.