Patients on opioid replacement therapy hospitalised with acute pain represent a clinical challenge and have poorer perioperative outcomes. There is limited evidence relating to acute pain management of this complex cohort. The primary objectives of this retrospective audit was to establish the number of patients who are admitted on opioid replacement therapy with an acute pain condition under surgical services and evaluate the management of these patients to determine consistency of pain management practices. Secondarily, we aimed to evaluate the documentation of opioid replacement therapy in clinical notes to determine adherence to operational protocols and record clinically relevant outcomes including infection or postoperative complication rates. Forty-four episodes of care for buprenorphine patients and 19 episodes of care for methadone patients were included. There was significant variability in inpatient opioid prescribing, including practice of dose modification, and there was high utilisation of additional opioids, although agent choice varied. Multimodal analgesia was utilised, especially following acute pain service review. There was an 11% readmission rate for complications of the initial presentation. Documentation at transitions of care was poor. There is a need for further clinical studies into specific acute pain management strategies, and their effect on clinically relevant outcomes, to guide consistent management practices.