The experiences of individuals with mental illness and addictions who frequently present to hospital emergency departments (EDs) have rarely been explored. This study reports findings from self-reported, quantitative surveys (n = 166) and in-depth, qualitative interviews (n = 20) with frequent ED users with mental health and/or substance use challenges in a large urban centre. Participants presented to hospital for mental health (35 %), alcohol/drug use (21 %), and physical health (39 %) concerns and described their ED visits as unavoidable and appropriate, despite feeling stigmatized by hospital personnel and being discharged without expected treatment. Supporting this population may require alternative service models and attention to staff training in both acute and community settings.