ABSTRACT OBJECTIVE To estimate age and sex-specific suicide rates, compare suicide rates between indigenous communities, and quantify the frequency of intrafamilial suicide clustering. METHODS We performed a retrospective cohort study involving 14,666 indigenous individuals in reservations in Dourados, state of Mato Grosso do Sul, Brazil, from 2003 through 2013 using national and local census. RESULTS The overall suicide rate was 73.4 per 100,000 person-years. Adolescent males aged 15-19 and girls aged 10-14 had the highest rates for each sex at 289.3 (95%CI 187.5-391.2) and 85.3 (95%CI 34.9-135.7), respectively. Comparing the largest reservations, Bororo had a higher suicide rate than Jaguapiru (RR = 4.83, 95%CI 2.85-8.16) and had significantly lower socioeconomic indicators including income and access to electricity. Nine of 19 suicides among children under 15 occurred in household clusters. Compared with adult suicides, a greater proportion of child (OR = 5.12, 95%CI 1.89-13.86, p = 0.001) and adolescent (OR = 3.48, 95%CI 1.29-9.44, p = 0.017) suicides occurred within household clusters. CONCLUSIONS High rates of suicide occur among children and adolescents in these indigenous reservations, particularly in poor communities. Nearly half of child suicides occur within household clusters. These findings underscore the need for broad public health interventions and focused mental health interventions in households following a suicide.