<b>Objective</b> To examine the effect of clinician designation on emergency department (ED) fast track performance.<br><b>Design and Setting</b> A retrospective audit of patients managed in the fast track area of an ED in metropolitan Melbourne, Australia.<br><b>Participants</b> Patients triaged to ED fast track from 1 January 2008 to 31 December 2008 (n=8714).<br><b>Main Outcome Measures</b> Waiting times in relation to Australasian triage scale (ATS) recommendations and ED length of stay (LOS) for non-admitted patients were examined for each clinician group.<br><b>Results</b> Compliance with ATS waiting time recommendations was highest (82.5%) for emergency nurse practitioners/candidates and lowest (48.2%) for junior medical officers. Median ED LOS was less than 3 h for non-admitted patients, and 85.8% of non-admitted fast track patients (n=6278) left the ED within 4 h. Patients managed by emergency nurse practitioners/ candidates had the shortest ED LOS (median 1.7 h) and patients managed by junior medical officers and locum medical officers the longest ED LOS (median 2.7 h) (x²=498.539, df=6, p<0.001).<br><b>Conclusions</b> Clinician designation does impact on waiting times and, to a lesser extent, ED LOS for patients managed in ED fast track systems. Future research should focus on obtaining a better understanding of the relationship between clinician expertise, time-based performance measures and quality of care indicators.<br>