Abstract: Patients with sickle cell disease (SCD) or cancer with bone metastasis often present to the emergency department (ED) for treatment of severe pain, and opioid analgesics remain first-line therapies for acute pain in the ED or after discharge. Policies aimed at improving the safety of opioid prescribing, such as state legislative mandates that prescribers register with or use prescription drug monitoring programs (PDMPs), may inadvertently limit access to opioids for these patients. We examined the association between implementation of PDMP mandates and changes in opioids dispensed to these patients following ED encounters.