As a continuation of efforts to elucidate the influence of ginseng upon nucleic acid content of various tissues, a study was carried out which measured testicular RNA and DNA contents of rats following administration of ginseng. Thirty male rats (body weight: 180 ~ 230 gm) were equally divided into a ginseng and a saline group. Once a day for 5 days they received subcutaneously 0.5 m1/100 gm body weight of ginseng extract solution (4 mg of ginseng alcohol extract in 1 ml of saline), and the same amount of satire, respectively. On the 5th experimental day, all animals were sacrificed 2 hours after the last medication and their testicular RNA and DNA contents were measured using the chemical method of Schmidt-Thannhauser-Schneider. Following results were obtained: 1. Testicular RNA and DNA contents were significantly higher in the ginseng group than in the saline group. 2. RNA/DNA ratio of the testis was lower in the ginseng group than in the saline group. However, the two groups did not differ significantly with regard to the RNA/DNA ratio. The ginseng is inferred to raise RNA and DNA contents of testis in rats.