The present study was designed by ip panaxatroil (5 mg/0.2 ml•d × 14 d) 24 h before and after 5 Gy whole-body X-irradiation in male rats to observe the radioprotective effects of panaxatroil on opioid peptides and immune functions. The results showed that the hypothalamic opioid peptide contents and the immune parameters of thymus and spleen cells all decreased 14 d after irradiation, while hypothalamic opioid peptide contents approached the control level and all immune parameters decreased in irradiation plus panaxatroil group but higher than that in control group. The above results suggest that panaxatroil may alleviate the decrease of hypothalamic opioid peptide contents and immune parameters of thymus and spleen cells, and have radioprotective effects.