Introduction: Inhaled low dose methoxyflurane (MEOF) was recently approved in Canada for the short-term relief of moderate to severe acute pain associated with trauma or interventional medical procedures in conscious adult patients. ADVANCE-ED is an ongoing phase IV, prospective open label study undertaken to generate real-world evidence to complement the global clinical development program through evaluation of the effectiveness of low dose MEOF in Canadian emergency departments (EDs). Methods: This multi-centre study is enrolling adult (≥18 yrs) patients with moderate to severe acute pain (NRS0-10 ≥ 4) associated with minor trauma. To address limitations from the pivotal study, this study allows patients who were excluded in the pivotal trials: namely, those with severe (≥7) pain, and those using OTC or stably dosed analgesics for other conditions, including chronic pain. Eligible patients receive a single treatment of up to 2 x 3 mL MEOF (2nd 3 mL to be provided only upon request), self-administered by the patient under medical supervision. Rescue medication is permitted at any time, if required. Results: Here we describe the patient demographics and treatment satisfaction (Global Medication Performance, GMP) at 50% enrolment (n = 49). Mean (SD) patient age is 48.0 (17.1) yrs and 55.1% are female. Mean pain (SD) reported at enrolment is 8.3 (1.5), with 73.4% of patients with NRS0-10 ≥ 8. Injuries are overwhelmingly limb trauma (87.8%). The most common type is sprain/strain (40.8%), followed by fracture (32.7%). At 5 minutes post-start of administration (STA) of MEOF, 80.4% of patients reported pain relief; this increased to 91.3% at 15 minutes, and 100% of patients reported pain relief by 30 minutes post-STA. GMP was assessed as “good”, “very good” or “excellent” by ≥80% of patients both 20 minutes post-start of administration (STA) of MEOF (83.3%) and at discharge (85.8%). When asked to what extent their expectation of pain relief had been met, 32.7% responded good, 26.5% responded “very good” and 22.4% responded “excellent”. Three quarters of enrolled patients (75.5%) did not require rescue medication. The most common (≥5%) treatment-related adverse events were dizziness (n = 14, 28.6%) and euphoric mood (n = 4, 8.2%). No serious adverse events have been reported. Conclusion: Based on 50% of the patients enrolled in this prospective, open label study, responses to inhaled low-dose MEOF are within expectation for both effectiveness and tolerability.