Objective Low back pain is frequently seen in patients visiting the ED, but many patients receive medical care with no demonstrable benefits. We studied the clinical characteristics of patients visiting two EDs in Santiago, Chile, and their management to evaluate how it adheres to evidence-based recommendations. Methods We studied 519 patients and retrieved their demographic and clinical data, imaging testing and treatments. We determined the effect of sex, age, time from initial symptoms, pain measured with the visual analogue scale, presence of nerve radiation and the presence of red flags and neurological impairment on image testing and the management received. Results Mean age was 43.8 years; 57.8% were females. Females presented more often red flags (7.3vs3%,P= 0.04) and worse pain (visual analogue scale = 7vs6,P= 0.04) than males. Imagings were performed in 18.9% of patients; they were more frequently performed in patients with neurological impairment (P= 0.03) and red flags (P= 0.01). Intravenous non-opioids were administered in 25.6%; opioids were administered in 40.1%. Median time in the ED was 91 min (range 18-591); 16 (3.08%) patients were admitted. Age (odds ratio [OR] 1.04 [1.03-1.05],P < 0.01) and red flags (OR 4.9 [1.60-20.08],P < 0.01) influenced imaging testing; pain intensity influenced opioid use (OR 1.6 [1.29-1.95],P < 0.01), hospital admissions (1.95 [1.14-3.33],P < 0.01) and time in the ED (beta= 0.5,P < 0.01). Conclusion Older age, the presence of red flags and pain intensity influenced the management of patients with low back pain in the ED. Future strategies should emphasise avoiding costly and ineffective management in these patients.