Deaths from opioid pain reliever overdose in the United States quadrupled between 1999 and 2013, concurrent with an increase in the use of the drugs. We used data from the Medical Expenditure Panel Survey to examine trends in opioid pain reliever expenditures, financing by various payers, and use from 1999 to 2012. We found major shifts in expenditures by payer type for these drugs, with private and public insurers paying a much larger share than patients in recent years. Consumer out-of-pocket spending on opioids per 100 morphine milligram equivalents (a standard reference measure of strength for various opioids) declined from $4.40 to $0.90 between 2001 and 2012. Since the implementation of Medicare Part D in 2006, Medicare has been the largest payer for opioid pain relievers, covering about 20–30 percent of the cost. Medicare spends considerably more on these drugs for enrollees younger than age sixty-five than it does for any other age group or than Medicaid or private insurance does for any age group. Further research is needed to evaluate whether payer strategies to address the overuse of opioids could reduce avoidable opioid-related mortality.