The burden of treatment-resistant depression (TRD) in Canada requires empirical characterization to better inform clinicians and policy decision-making in mental health. Towards this aim, this study utilized the Institute for Clinical Evaluative Sciences (ICES) databases to quantify the economic burden and resource utilization of Patients with TRD in Ontario. TRD, Non-TRD Major Depressive Disorder (Non-TRD MDD) and Non-MDD cohorts were selected from the ICES databases between April 2006-March 2015 and followed-up for at least two years. TRD was defined as a minimum of two treatment failures within one-year of the index MDD diagnosis. Non-TRD and Non-MDD patients were matched with patients with TRD to analyze costs, resource utilization, and demographic information. Out of 277 patients with TRD identified, the average age was 52 years (SD 16) and 53% were female. Compared to Non-TRD, the patients with TRD had more all-cause visits to outpatient (38.2 vs. 24.2) and emergency units (2.7 vs. 2.0) and more depression-related visits to GPs (3.06 vs. 1.63) and psychiatrists (5.88 vs. 1.95) (all p < 0.05). The average two-year cost for TRD patients was $20,998 (CAD). This study included patients with only public plan coverage; therefore, overall TRD population and cash and private claims were not captured. Patients with TRD exhibit a significantly higher demand on healthcare resources and higher overall payments compared to Non-TRD patients. The findings suggest that there are current challenges in adequately managing this difficult-to-treat patient group and there remains a high unmet need for new therapies. Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.