Using the linked data from the project: Health service use of people with opioid use disorders, we were able to show that, among people with opioid use disorder, urgent ED presentations and associated costs are reduced during periods of OAT relative to periods out of OAT. This difference was seen regardless of geographical remoteness and suggests that life-threatening events (e.g. overdose) are reduced in frequency while in OAT.  A more complex picture was identified in relation to low acuity ED presentations.  For OAT clients in major cities, low acuity presentations were significantly less frequent during periods of treatment compared to time out of treatment. This was not the case in regional/remote areas.  This may reflect difficulties in accessing OAT, and possibly primary care more broadly, in regional/remote NSW.  People living outside major cities may have difficulties accessing a community-based general practitioner who prescribes OAT.  The current OATS project has identified that OAT prescribing is increasingly concentrated in a small group of mature prescribers, and new prescribers have not been retained. There is a need to identify and respond to the reasons that contribute to newer prescribers to cease prescribing and put in place strategies to increase retention and broaden the base of doctors involved in such prescribing.