BackgroundLow back pain (LBP) is ranked in the top 10 conditions presenting to emergency departments (ED) in Australia. We aimed to investigate ED re-presentation rates and length of stay (LOS) of patients with LBP, including associated factors. MethodsWe reviewed medical records of three EDs in Sydney, Australia from January 2016 to October 2021. The primary outcome was the proportion of episodes of non-serious LBP with at least one re-presentation within 12 months. Secondary outcomes were re-presentation rates within 3-days, 1-week, 1-month, 3-months, 6-months, and mean LOS. Multivariable logistic regression analyses were performed to investigate the associated factors with re-presentation and prolonged stay (>4 h) and reported as adjusted odds ratios (aORs) and 95% confidence intervals (95% CI). ResultsOf 8289 episodes of non-serious LBP, 7.7% included at least one re-presentation within 12 months. There were only 14 re-presentations (0.2%) where the diagnosis changed from non-serious LBP at the index visit to serious spinal pathology at the repeat visit. The overall mean LOS was 4.1 h, and 26.9% of patients stayed in the ED for >4 h. Those who received opioids (aOR: 1.31; 95% CI: 1.08–1.59) were more likely to re-present. In contrast, patients receiving imaging were less likely to re-present (aOR: 0.78, 95% CI: 0.65–0.94). Receiving imaging (aOR: 2.83; 95% CI: 2.56–3.13) and opioids (aOR: 1.64; 95% CI: 1.47–1.82) increased the odds of prolonged stay. ConclusionA re-presentation within 12 months occurs in 7.7% of episodes of LBP in ED. Over one-quarter of patients stayed longer than 4 h.