Background: Older HNC survivors often experience post-treatment pain, and they have concerningly high rates of unsafe opioid prescribing (e.g., high doses, concurrent benzodiazepines). Interventions to improve opioid safety should target providers who prescribe opioids to HNC survivors. We hypothesized that oncologists were responsible for most opioid prescribing to HNC survivors, but that involvement of primary care providers (PCPs) as prescribers increased over time after treatment. Methods: Using linked Surveillance, Epidemiology, and End Results (SEER) registry and Medicare claims data, we identified adults age >65 diagnosed 2014-2017 with stage I-III HNC with ≥6 months treatment-free follow-up prior to censoring at further treatment, new cancer, hospice, death, or end 2019. Starting 1 month after treatment completion, all opioid fills were assigned to a prescriber specialty: oncology (medical, radiation, surgical), surgery, primary care (internal medicine, family practice, geriatrics), pain, or other. Prescriber patterns were summarized at the fill and patient levels for each year of follow-up. Results: Among 5494 HNC survivors with median 2.1 years of treatment-free follow-up, 3092 (56%) had ≥1 opioid fill. At the fill level, almost half of all opioids (47%) were dispensed in the first year after treatment completion, with fewer fills each subsequent year. Contrary to our hypothesis, only 9% of all fills were prescribed by oncologists. Half of all fills were prescribed by PCPs; 14% were prescribed by pain specialists and 9% by surgeons. At the patient level, on average, each survivor had 34% of their opioid fills prescribed by primary care providers, followed by 24% by surgeons and 10% by oncologists. The proportion of survivors’ fills prescribed by PCPs remained high (36%-42% of each survivor’s fills) across all years, while proportion of each survivor’s fills prescribed by oncologists declined from 14% to 2% over years of follow-up. (See Table). Conclusions: PCPs prescribe a greater proportion of HNC survivors’ opioids than oncologists and surgeons combined. While oncologists’ and surgeons’ role as opioid prescribers declines over time, primary care involvement in opioid prescribing remains high throughout survivorship, suggesting that PCPs manage cancer-related pain, non-cancer pain is prevalent after HNC, or both. Interventions to address unsafe opioid use among HNC survivors should target the primary care setting, as is typical for opioid-reduction efforts in the non-cancer population.