The treatment of chronic pain remains an enormous challenge in the United States. Opioid analgesics are an important component of pharmacotherapy for chronic pain and have proven efficacy in the management of cancer and noncancer chronic pain. The newest addition to oral opioid pharmacotherapy is oral oxymorphone, a semisynthetic opioid agonist that is now available in oral immediate-release (IR) and extended-release (ER) formulations. This review discusses the pharmacology, pharmacokinetics, pharmacodynamics, pharmacotherapeutics, and clinical use of oral oxymorphone IR and ER formulations for the management of moderate to severe pain for different types of patients in a variety of settings. Two published studies evaluated the efficacy and safety of oxymorphone IR in patients with moderate to severe postoperative pain and demonstrated that it provides rapid and effective analgesia and is generally well tolerated. Six published randomized controlled trials and three published open-label studies evaluated the efficacy and safety of oxymorphone ER for chronic cancer or noncancer pain. These trials found analgesic efficacy and tolerability comparable to that provided by morphine controlled release (CR) or oxycodone CR; treatment effects with oxymorphone ER were durable for treatment periods of 12 weeks at the same dose or up to 1 year with little dose escalation. Titrated doses of oxymorphone ER were effective and generally well tolerated in both opioid-experienced and opioid-naïve patients. Aspects of oxymorphone metabolism and limited protein binding may simplify treatment in certain populations.