Despite increasing rates of prescription opioid (PO) misuse in adults 50 years of age and older, little research has investigated such misuse in this population. This work aimed to examine sources of misused opioid medication in adults 50 years and older, with comparisons to younger groups. Data were from the 2009 to 2014 National Survey on Drug Use and Health surveys. Prevalence rates of PO sources, misuse, and PO use disorder (POUD) symptoms were estimated. Design-based logistic regression investigated age-based differences in these factors and the association of sources with POUD symptoms and other concurrent substance use. Nearly half (47.7%) of adults 65 years and older used physician sources for past 30-day PO misuse, with the second highest rates in those 50 to 64 years old (39.2%). Conversely, use of theft (5.3%), purchases (8.5%), or friends/family (for free; 23.2%) to obtain opioids were least common in adults 65 years and older, with prevalence rates of these sources in those 50 years and older closer to those of younger groups. Across those 50 years and older, use of purchases, physician, or multiple sources were associated with elevated POUD symptom prevalence. Older adults, particularly those 65 years and older, use a different pattern of PO sources than adolescents or younger adults, and those using physician sources have elevated POUD symptoms. Physicians are a key avenue for older adults to obtain opioids for misuse, highlighting the potential role of clinicians in limiting such misuse.