The increased use of opioids in the treatment of chronic pain encourages the search for drugs with low abuse and tolerance potential but with potent analgesic activity. Opioid agonist-antagonists and partial agonists have less abuse potential than do mu opioid receptor agonists such as morphine, and have been used for many years for their analgesic affects. Recently they have been approved for treatment of opioid addiction. As a guard against abuse, an opioid antagonist, such as naloxone, is added to some opioid formulations. Doctors are often hesitant to prescribe agonist-antagonists and partial agonists to opioid-tolerant patients, fearing that these drugs may precipitate withdrawal. Can drugs being used safely for addiction treatment also safely replace opioid agonists to provide analgesia in chronic pain patients who are opioid-tolerant?