Prescription drug monitoring programs (PDMPs) are a response to the prescription opioid epidemic, but their impacts on prescribing and health outcomes remain unclear, with conflicting reports. We sought to determine if prescriber use of Oregon's prescription drug monitoring program (PDMP) led to fewer high-risk opioid prescriptions or overdose events. We conducted a retrospective cohort study from October, 2011 through October, 2014, using statewide PDMP data, hospitalization registry, and vital records.Early PDMP registrants (n=927) were matched with clinicians who never registered during the study period, using baseline prescribing metrics in a propensity score. Generalized estimating equations were used to examine prescribing trends following PDMP registration, using 2-month intervals. We found a statewide decline in measures of per capita opioid prescribing. However, compared with non-registrants, PDMP registrants did not subsequently have significantly fewer patients receiving high-dose prescriptions; overlapping opioid and benzodiazepine prescriptions, inappropriate prescriptions, prescriptions from multiple prescribers, or overdose events. At baseline, frequent PDMP users wrote fewer high-risk opioid prescriptions than infrequent users; this persisted during follow-up with few significant group differences in trend. Thus, although opioid prescribing declined statewide after implementing the PDMP, registrants did not demonstrate greater declines than non-registrants.