Numerous studies have demonstrated the capacity of music to modulate pain. However, the neurophysiological mechanisms responsible for this phenomenon remain unknown. In order to assess the involvement of descending modulatory mechanisms in the modulation of pain by music, we evaluated the effects of musical excerpts conveying different emotions (pleasant-stimulating, pleasant-relaxing, unpleasant-stimulating) on the spinally mediated nociceptive flexion reflex (or RIII), as well as on pain ratings and skin conductance responses. The RIII reflex and pain ratings were increased during the listening of unpleasant music compared with pleasant music, suggesting the involvement of descending pain-modulatory mechanisms in the effects of musical emotions on pain. There were no significant differences between the pleasant-stimulating and pleasant-relaxing musical condition, indicating that the arousal of music had little influence on pain processing.