Opioid overprescribing is a major driver of the current opioid overdose epidemic. However, annual opioid prescribing in the USA dropped from 782 to 640 morphine milligram equivalents per capita between 2010 and 2015, while opioid overdose deaths increased by 63%. To better understand the role of prescription opioids and health care utilization prior to opioid-related overdose, we analyzed the death records of decedents who died of an opioid overdose in Illinois in 2016 and linked to any existing controlled substance monitoring program (CSMP) and emergency department (ED) or hospital discharge records. We found that of the 1893 opioid-related overdoses, 573 (30.2%) decedents had not filled an opioid analgesic prescription within the 6 years prior to death. Decedents without an opioid prescription were more likely to be black (33.3% vs 20.2%, p < .001), Hispanic (16.3% vs 8.8%, p < .001), and Chicago residents (46.8% vs 25.6%, p < .001) than decedents with at least one filled opioid prescription. Decedents who did not fill an opioid prescription were less likely to die of an overdose involving prescribed opioids (7.3% vs 19.5%, p < .001) and more likely to fatally overdose on heroin (63% vs 50.4%, p < .001) or fentanyl/fentanyl analogues (50.3% vs 41.8%, p = .001). Between 2012 and the time of death, decedents without an opioid prescription had fewer emergency department admissions (2.5 ± 4.2 vs 10.6 ± 15.8, p < .001), were less likely to receive an opioid use disorder diagnosis (41.3% vs 47.5%, p = .052), and were less likely to be prescribed buprenorphine for opioid use disorder treatment (3.3% vs 8.6%, p < .001). Public health interventions have often focused on opioid prescribing and the use of CSMPs as the core preventive measures to address the opioid crisis. We identified a subset of individuals in Illinois who may not be impacted by such interventions. Additional research is needed to understand what strategies may be successful among high-risk populations that have limited opioid analgesic prescription history and low health care utilization.