Objective The aim of this study was to compare emergency department (ED) key performance indicators for patients presenting with low back pain and seen by an advanced musculoskeletal physiotherapist (AMP) with those seen by other non-AMP clinicians (ED doctors and nurse practitioners). Methods A retrospective audit (October 2012–September 2013) was performed of data from three metropolitan public hospital EDs to compare patients with low back pain seen by AMP and non-AMP clinicians. Outcome measures included ED length of stay, ED wait time, admission rates and re-presentation to the ED. Results One thousand and eighty-nine patients with low back pain were seen during AMP service hours (360 in the AMP group, 729 in the non-AMP group). Patients seen by the AMP had a significantly shorter ED wait time (median 13 vs 32 min; P < 0.001) and ED length of stay (median 141 vs 175 min; P < 0.001). Significantly fewer patients seen by the AMP were admitted (P < 0.001), and this difference remained after accounting for the difference in triage code between the groups. Conclusions Improved ED metrics were demonstrated in patients with low back pain when managed by an AMP compared with patients seen by doctors and nurse practitioners. What is known about the topic? There is a growing body of literature regarding the role of AMPs in the Australian healthcare system in providing clinical services for patients with musculoskeletal conditions, including settings such as the ED. AMPs have proven to be safe and cost-effective, achieving high patient satisfaction and improved patient outcomes. However, there is little to no information regarding their effect on ED metrics, such as ED length of stay, wait time and admission rates for patients presenting to the ED with low back pain. What does this paper add? This paper demonstrates improved ED metrics for patients presenting to the ED with low back pain when seen by an AMP compared with patients seen by doctors and nurse practitioners. The specific improved metrics for these patients were decreased admission rates, decreased ED length of stay and decreased wait time. What are the implications for clinicians? This paper provides evidence that the AMPs effectively discharge patients admitted to the ED in a timely manner, without evidence of increased readmissions, compared with their medical and nursing colleagues. Support for the role of the AMP within the ED setting is strengthened by these results.