High levels of aggression towards staff in healthcare settings have been reported. It seems likely that workers in Opioid Substitution Therapy (OST) would be at increased risk of adverse events and their consequences.This study aimed to establish if practitioners who provide OST are experiencing negative outcomes, specifically aggression, distress, and burnout, and to identify if workload and professional affiliation were associated with these risks.A survey was conducted of OST practitioners in a single geographical region of New Zealand (population approx. 344,000). The survey asked for demographics (including caseloads), Perception of Patient Aggression Scale New Zealand Revision (POPAS-NZ), Kessler 10 (K10), Short Post-Traumatic Stress Disorder Rating Interview (SPRINT), and Abbreviated Maslach Burnout Inventory (aMBI) and two qualitative questions asking about the best and worst aspects of working in OST.All recorded OST workers in the region (n = 181) were invited to participate, 95 practitioners responded to the survey (52.4%). This group included pharmacists, doctors, nurses, social workers and addiction workers. Results indicated aggression, distress, and burnout were being experienced by practitioners. Number of patients seen by a practitioner significantly increased risk of aggression (F(1,90) = 14.14, p < 0.001). Psychiatrists were the most at risk profession (p = 0.016). Burnout responses were high for around 20% of practitioners, with low numbers meeting criteria for distress and PTSD. Positive things about working in OST were relationships with patients, appreciating patient outcomes and positive team environments. Negative aspects were patient behaviours, maintaining empathy, and, administration tasks.Aggression was a workplace hazard for OST clinicians. Low rates of distress and PTSD symptoms were reported and some evidence of practitioner burnout. Practitioners reported positive relationships, making a difference and teamwork may have been improving this area of mental health work.