Objective : In recent years, many investigators have questioned whether the analgesic effect of acupuncture is simply related to the stress-induced analgesia (SIA). However, there has been lack of studies on this issue. In this study, the stress levels induced by manual acupunctures are compared with the stress in animal experiment models. The experiments have been carried out with Sprague Dawley (SD) rats. Method : For stress level evaluation, Hot plate test has been used. Maximum Possible Effect (MPE) has been measured by checking the pre-test time and post-test time. Cortisol and corticosterone concentrations in serum were measured by enzyme-linked immunosorbent assay (ELISA). Results : In the hot plate test, MPE values of post-test time were significantly decreased after 10 minutes than after 5 minutes. Therefore, optimal time interval was chosen as 10 minutes. There was significant difference of MPE values between Suspension group and all other treatment groups. However, there were no significant differences of MPE values between Sham group and all other treatment groups. However, MPE values showed tendency to decrease when acupuncture needle diameter increased. MPE values of ST040, ST040(lido), NAP040(lido) groups were markedly decreased than that of Suspension group, while that of NAP040 group was substantially increased than that of Sham group increased in acupoint and nonacupoint models. Serum cortisol concentrations of treatment groups were not significantly different from that of Suspension and Sham groups. Serum corticosterone concentration of 0.25 mm group was substantially increased than that of compared with Sham group. Serum cortisol and corticosterone concentrations of treatment groups were not significantly different from those of Suspension and Sham groups in acupoint and nonacupoint models. Conclusion : From hot plate test and serum stress hormones concentrations, it is found that manual acupuncture treatment induces negligible stress or SIA on ST36. And the stress induced by manual acupuncture is more closely related to acupuncture point needlings than diameters of acupuncture needles.