Introduction — Exposure to opioids is largely unavoidable after major surgery since they are routinely used to treat postoperative pain. Nonetheless, continued long-term opioid use has negative health consequences, including opioid dependence. Patients and healthcare providers are therefore concerned about long-term postoperative opioid use. There are limited data on the risk of previously opioid-naïve individuals developing persistent postoperative opioid use. In a recent population-based cohort study, we found that 3% of previously opioid-naïve patients continued to use opioids at three months after major elective surgery in Ontario, Canada. Importantly, the risk of persistent opioid use over longer time frames after surgery remains unclear. We therefore conducted a follow-up study to measure rates of ongoing opioid use up to one-year after major surgery.