Management of chronic noncancer pain (CNCP) requires a comprehensive assessment of the patient, the institution of a structured treatment regimen, an ongoing reassessment of the painful condition and its response to therapy, and a continual appraisal of the patient's adherence to treatment. For many patients with CNCP, the analgesic regimen will include opioids. Physicians should consider the available evidence of efficacy, the routes of administration, and the pharmacokinetics and pharmacodynamics of the various formulations as they relate to the temporal characteristics of the patient's pain. When making initial decisions, physicians should decide whether to prescribe a shortacting opioid (SAO) with a relatively quick onset of action and short duration of analgesic activity, a long-acting opioid (LAO) with a longer duration of analgesic action but a potentially longer onset of action, or both. Studies suggest that SAOs and LAOs are both effective for most types of CNCP. A review of published studies found no data to suggest that either SAOs or LAOs are generally more efficacious for treating any particular CNCP condition. The LAOs may provide more stable analgesia with less frequent dosing; however, opioid therapy should be tailored to the pain state and the individual patient, and SAOs may be appropriate for some patients with CNCP. MEDLINE and PubMed searches were conducted to locate relevant studies published from January 1975 to April 2008 using the following search terms: opioids, short-acting opioids, long-acting opioids, chronic pain, chronic pain AND opioids, and narcotics. English-only randomized controlled trials and nonrandomized studies were considered.Mayo Clin Proc. 2009;84(7):602-612 ADL = activities of daily living; AE = adverse effect; ATC = around-theclock; BPI = Brief Pain Inventory; CNCP = chronic noncancer pain; CR = controlled-release; DN = diabetic neuropathy; ER = extended-release; IR = immediate-release; LAO = long-acting opioid; LBP = low back pain; NSAID = nonsteroidal anti-inflammatory drug; PHN = postherpetic neuralgia; QOL = quality of life; SAO = short-acting opioid; SNRI = serotonin norepinephrine reuptake inhibitor; SR = sustained-release; TCA = tricyclic antidepressant