Introduction: Choosing Wisely Canada guidelines suggest that in the absence of red flags or clinical indicators suggestive of serious underlying conditions, physicians should not order radiological images for patients presenting with non-specific low back pain, and current recommendations do not endorse routine prescribing of opioids for this condition. The objective of this study was to determine how many patients presenting to the ED with non-traumatic low back pain have spinal imaging and how many are discharged home on opioids. Methods: We conducted a retrospective medical record review for adult (>17 years) patients presenting to an academic tertiary care ED with non-traumatic low back pain from April 1st 2014 to March 31st 2015 (pre-guideline) and April 1st 2017 to March 31st 2018 (post-guideline). Patients were excluded if they were >70 years old, were not discharged home, had a traumatic injury, features of cauda equina syndrome, weight loss, history of cancer, fever, night sweats, chronic use of systemic corticosteroids, chronic use of illicit intravenous drugs, first episode of low back pain over 50 years of age, abnormal reflexes, loss of motor strength or loss of sensation in the legs. Results: 1060 (545 pre-guideline, 515 post-guideline) were included. Mean (SD) age was 39.6 (12.3) years and 549 (51.8%) were female. Pre-guideline, 45 (8.3%) patients had spinal imaging, compared to 39 (7.6%) post-guideline (Δ 0.7%; 95% CI: −2.6% to 4.0%). Of the 84 (7.9%) patients who had spinal imaging, 4 (8.9%) had pathologic findings pre-guideline, compared to 10 (25.6%) patients post-guideline. The proportion of patients discharged home with a prescription for opioids was lower after the Choosing Wisely Canada guidelines (40.9% vs. 11.1%; Δ29.8%; 95% CI: 24.8% to 34.7%). Conclusion: Choosing Wisely Canada guidelines did not appear to alter the rate of imaging for patients presenting to the ED with non-traumatic low back pain. Overall the rate of spinal imaging was lower than expected. The proportion of patients who were discharged home with a prescription for opioids was lower after the Choosing Wisely Canada guidelines, however we don't know if this represents an overall trend in the reduction of opioid prescribing, or a specific change in practice related to the ED management of low back pain.