SUMMARYAcanthopanax Koreanum stem (AK) has been used in Korea as a tonic and sedative as well as a drug with ginseng like activities. The purpose of our present study was to investigate the effects of AK extract (AKE) and Eleutheroside E, major component of AKE on an exacerbated immune function through utilization of protein-energy malnutrition (PEM) diet by using forced swimming test (FST). The immobility time were significantly decreased in the AKE or Eleutheroside E-administrated group compared with the control group on the FST (P < 0.05). The level of blood parameters were not changed significantly. PEM-induced weight loss of mice was reduced by oral administration of 500 mg/kg AKE. AKE oral administration improved the nutritional status such as the food efficiency ratio and the adrenal gland weight. AKE treatment significantly increased the production of interferon (IFN)-γ compared with unstimulated splenocytes but not interleukin (IL)-4. Eleutheroside E also significantly increased the IFN-γ production but not IL-2 and IL-4 in T cell line, MOLT-4 cells. These results suggest that AKE and Eleutheroside E may influence to immune-enhancing through increasing the physical endurance capacity and immune cell activation.