BACKGROUND: Emergency department visits as a first point of contact for people with mental illness may reflect poor access to timely outpatient mental health care. We sought to determine the extent to which immigrants use the emergency department as an entryway into mental health services. METHODS: We used linked health and demographic administrative data sets to design a population-based cohort study. We included youth (aged 10-24 yr) with an incident mental health emergency department visit from 2010 to 2014 in Ontario, Canada (n = 118 851). The main outcome measure was an emergency department visit for mental health reasons without prior mental health care from a physician on an outpatient basis. The main predictor of interest was immigrant status (refugee, non-refugee immigrant and non-immigrant). Immigrantspecific predictors included time since migration, and region and country of origin. We used Poisson models to estimate adjusted rate ratios (aRRs) and 95% confidence intervals (CIs). RESULTS: The cohort included 2194 (1.8%) refugee, 6680 (5.6%) non-refugee immigrant and 109 977 (92.5%) nonimmigrant youth. Rates of first mental health contact in the emergency department were higher among refugee (61.3%) and non-refugee immigrant youth (57.6%) than non-immigrant youth (51.3%) (refugee aRR 1.17, 95% CI 1.13-1.21; non-refugee immigrant aRR 1.10, 95% CI 1.08-1.13). Compared with non-refugee immigrants, refugees had a higher rate of first mental health contact in the emergency department (aRR 1.06, 95% CI 1.02-1.11). We also observed higher rates among recent versus longer-term immigrants (aRR 1.10, 95% CI 1.05-1.16) and immigrants from Central America (aRR 1.17, 95% CI 1.08-1.26) and Africa (aRR 1.15, 95% CI 1.06-1.24) versus from North America and Western Europe. INTERPRETATION: Immigrant youth are more likely to present with a first mental health crisis to the emergency department than non-immigrants, with variability by region of origin and time since migration. Immigrants may face barriers to access and use of outpatient mental health services from a physician. Efforts are needed to reduce stigma and identify mental health problems early, before crisis, among immigrant populations.