To investigate factors associated with anaemia in preschool children. A home survey was conducted in 2018. Anaemia in children (capillary blood Hb level < 110 g/l) was the outcome, and socio-economic, demographic and health factors of the mother and child were the independent variables. The measure of association was the prevalence ratio, and its 95 % CI was calculated using Poisson's regression with robust variance and hierarchical selection of independent variables. Afro-descendants communities living in the state of Alagoas, northeast Brazil. Children aged 6-59 months and their mothers (n 428 pairs). The prevalence of child anaemia was 38·1 % (95 % CI 33·5, 42·7). The associated factors with child anaemia were male sex, age < 24 months, larger number of residents at home (> 4), relatively taller mothers (highest tertile) and higher z-score of BMI for age, after further adjustment for wealth index, vitamin A supplementation in the past 6 months and clinical visit in the last 30 d. The high prevalence of anaemia observed reveals a relevant public health problem amongst children under five from the quilombola communities of Alagoas. Considering the damage caused to health and multiplicity of risk factors associated with anaemia, the adoption of intersectoral strategies that act on modifiable risk factors and increase vigilance concerning those that are not modifiable becomes urgent.