Background　Opioids are the most powerful analgesics for the treatment of acute pain， chronic pain and cancer pain. Although opioids have analgesic effect， long term opioids exposure can induce many side effects including morphine tolerance and hyperalgesia. The use of opioids， therefore， is largely limited in clinical settings.　Objective　The relevant literatures in recent years involved in the role of peroxynitrite in morphine tolerance and hyperalgesia were summarized， which helps readership to update the latest information about this topic.　Content　The generation of peroxynitrite， eliminating methods and the role of peroxynitrite in opioids tolerance or hyperalgesia were reviewed in this article. Those researches suggest that peroxynitrite plays an important role in morphine tolerance and hyperalgesia mainly through nitrating protein tyrosine residues， activating the neuroinflammation and promoting neuron apoptosis.　Trend　Since the effect of peroxynitrite is widely acknowledged， peroxynitrite may become a new target to relieve pain in the clinical setting.