Background: We studied the effect of the Covid-19 pandemic on child eating disorder hospitalizations in Quebec, Canada. Quebec had one of the strictest lockdown measures targeting young people in North America. Methods: We analyzed eating disorder hospitalizations in children aged 10-19 years before and during the pandemic. We used interrupted time series regression to assess trends in the monthly number of hospitalizations for anorexia nervosa, bulimia nervosa, and other eating disorders before the pandemic (April 2006 to February 2020), and during the first (March to August 2020) and second waves (September 2020 to March 2021). We determined the types of eating disorders requiring hospital treatment and identified the age, sex and socioeconomic subgroups that were most affected. Results: Hospitalization rates for eating disorders increased during the first (6.5 per 10,000) and second waves (12.8 per 10,000) compared with the period before the pandemic (5.8 per 10,000). The increase occurred for anorexia nervosa as well as other types of eating disorders. The number of girls and boys aged 10-14 years admitted for eating disorders increased during wave 1. Wave 2 triggered an increase in eating disorder admissions among girls aged 15-19 years. Hospitalization rates increased earlier for advantaged than disadvantaged youth. Conclusions: The Covid-19 pandemic affected hospitalizations for anorexia nervosa as well as other eating disorders, beginning with girls aged 10-14 years during wave 1, followed by girls aged 15-19 years during wave 2. Boys aged 10-14 years were also affected, as well as both advantaged and disadvantaged youth.