OBJECTIVES: Most US studies of national trends in medical and nonmedical use of prescription opioids have focused on adults. Given the limited understanding in these trends among adolescents, we examine national trends in the medical and nonmedical use of prescription opioids among high school seniors between 1976 and 2015.METHODS: The data used for the study come from the Monitoring the Future study of adolescents. Forty cohorts of nationally representative samples of high school seniors (modal age 18) were used to examine self-reported medical and nonmedical use of prescription opioids.RESULTS: Lifetime prevalence of medical use of prescription opioids peaked in both 1989 and 2002 and remained stable until a recent decline from 2013 through 2015. Lifetime nonmedical use of prescription opioids was less prevalent and highly correlated with medical use of prescription opioids over this 40-year period. Adolescents who reported both medical and nonmedical use of prescription opioids were more likely to indicate medical use of prescription opioids before initiating nonmedical use.CONCLUSIONS: Prescription opioid exposure is common among US adolescents. Long-term trends indicate that one-fourth of high school seniors self-reported medical or nonmedical use of prescription opioids. Medical and nonmedical use of prescription opioids has declined recently and remained highly correlated over the past 4 decades. Sociodemographic differences and risky patterns involving medical and nonmedical use of prescription opioids should be taken into consideration in clinical practice to improve opioid analgesic prescribing and reduce adverse consequences associated with prescription opioid use among adolescents.