In the present experiment, we examined involvement of bradykinin and NGF in DOMS using a rat model of DOMS in which we previously showed the existence of mechanical hyperalgesia (Taguchi et al., 2005a) and increased mechanical sensitivity of muscle thin-fiber afferents (Taguchi et al., 2005b). We found that bradykinin triggers development of muscular mechanical hyperalgesia and NGF serves in its maintenance by sensitizing muscle C-fiber receptors to mechanical stimulation.