Injuries are a leading cause of death, morbidity and potential years of life lost among people in Canada. [1][2][3] Human behavioural changes during the COVID-19 pandemic have altered the injury landscape, with fewer sports-related injuries, motor vehicle collisions and falls, and a greater proportion of injuries occurring in the home. [4][5][6][7] Unintentional poisonings, specifically overdoses and alcohol-induced deaths, have contributed to the excess mortality rate observed during the pandemic.Throughout the pandemic, self-reported alcohol and cannabis use, and hospital discharges related to substance use have increased. [8][9][10][11][12] With public health measures encouraging people to stay home and limit social gatherings, people in Canada have changed their substance consumption habits by increasing consumption, changing the substances they normally use and using alone more frequently. [13][14][15][16][17][18] In addition, border closures, supply chain disruptions and increased pricing have altered the availability and toxicity of the illegal drug supply. 13,[19][20][21][22] As the pandemic continues to evolve and impose changes to human behaviour, as well as access to support programs and services, the injury epidemiology and substance use patterns in Canada may also change. 23,24 Studies conducted during the pandemic have shown an increase in substance-related hospital discharges, as well as overall changes in the injury landscape during the pandemic. Based on available evidence and changes to social behaviours, we suspect increased rates of hospital discharges for substance-related injuries in Canada during the pandemic. In the present study, we sought to evaluate monthly changes in hospital discharges for substance-related injuries during the first year of pandemic compared with before the pandemic. We also sought to identify subpopulations (based on age group, sex and substance type) that were greatly affected by substance-related injuries during the first year of the pandemic.