Plants have a potential to produce a large number of important metabolites such as pharmaceuticals, food additives, pigments, flavors, fragrances, and fine chemicals. Large-scale plant cell and tissue cultures for producing useful products has been considered an attractive alternative to whole plant extraction for obtaining valuable chemicals. In plant cell and tissue cultures, cell growth and metabolite production are influenced by nutritional and environmental conditions as well as physical properties of the culture system. To obtain a high growth rate of plant cell and tissue cultures, the culture conditions should be maintained at an optimum level. We studied the relationship between inoculum conditions and the growth of Panax ginseng hairy root culture, and found that the growth rate varied with the inoculum conditions such as the number of root tips, the length of root tips, the part of root tips, and the inoculum size and age of hairy roots.