Various rates of 2,4-D were sprayed on 2 and 3 year old ginseng plants as foliar spray to define the critical concentration. No apparent plant injury was noticable for those ginseng plants when application concentration of 2,4-D doubled the recommended dosage (70 ml/10a). Neither abnormal foliar change occurred nor any inhibition in leaf and stem growth was resulted for the plants treated with 2,4-D concentrated two times of the recommended dosage. When the rates of 2,4-D application were increased greater than this level, injury ratings increased linearly with the rates of 2,4-D application and plant you was inhibited. Ethylene gas was not produced from the ginseng plant treated with 2 times concentrated 2,4-D, however the ginseng plants produced 0.03 to 0.09 ppm ethylene gas when the rate of application were increased 3 and 4 times, respectively. On the other hand the soybean treated with the recommended amount of 21-D produced ethylene gas of 10-20 times higher compared with ginseng plants and died. Photosynthesis ability of the ginseng leaf was significantly decreased by 2,4-D foliar application but it was recovered 4 weeks after 2,4-D foliar treatment. The herbicide 2,4-D was applicated to 2,3 and 4 years old ginseng plants as foliar spray with the rates of 0.5, 1.0, 1.5 and 2.0 times of the recommended dosage to define the effects of 2,4-D on the plant growth and root yield of the ginseng. There were no significant differences in the leaf and stem growth between untreated and 2,4-D treated plant. Berry maturing of 3 and 4 year old ginseng was not influenced by 2,4-D. The root weight of 4 years old ginseng plant was not reduced by application of 2,4-D concenrated 2 times of the recommended dosage, Application time of the herbicide 2,4-D had no effects on the leaf or stem growth of 2,3 and 4 year old year old ginseng plants. When the ginseng seedling was treated with 2,4-D, detrimental phenomena as stem bending and docoration of seedling leaf margin occurred, but stem bending was recovered in a few day s. Keywords Panax ginseng C.A. Meyer, 2,4-D , herbicide.