Introduction: Use of diagnostic imaging in the emergency department (ED) has significantly increased over time. The decision to use a certain type of imaging, if any at all, is not always clear. Accordingly, concerns of appropriateness are justified. A starting point to assess imaging appropriateness is to measure variation in its use. It has been suggested that where large variation exists, there may be inappropriate use. Methods: We retrospectively studied consecutive ED visits at North York General Hospital between April 1, 2009 and March 31, 2013 (n = 316,251), and developed a two-level hierarchical logistic regression model to quantify inter-physician variation in imaging use (high-cost imaging: computed tomography (CT), magnetic resonance (MR), nuclear medicine; low-cost: plain radiography, ultrasound) in the ED after adjusting for patient-, visit- and physician-level factors. Results: Plain radiography or ultrasound examinations were performed during 36.3% of ED visits; CT, MR, or nuclear medicine examinations were performed during 10.6% of ED visits; 4.1% of ED visits had both high- and low-cost imaging. After adjusting for patient-, visit- and physician-specific factors, only 2.4% and 2.2% of the variation regarding whether or not an ED visit resulted in at least one high-cost and low-cost imaging test, respectively, was attributable to individual physician practice patterns. Physicians who had a tendency to obtain more low-cost imaging also obtained more high-cost imaging, and those who obtained less low-cost imaging also obtained less high-cost imaging. Conclusion: Only a small portion of the variation in imaging use was attributed to differences in ED physician ordering patterns, however, these findings may still help promote discussion among clinicians, and improve imaging utilization.