BackgroundWhether or not the Water, Sanitation and Hygiene (WASH) conditions in which children under five live determine their nutritional status is still under discussion. The work aimed to study the effects of household WASH conditions to which children under five are exposed on their nutritional status in Benin.MethodsThe study utilized a cross-sectional design and consisted of secondary analyses using datasets from the fifth Demographic and Health Survey (DHS-V) conducted in Benin. Stunting, wasting and underweight were the dependent variables. The WASH conditions in which children live were evaluated in the immediate environment, i.e., at the level of their households. After describing the study variables, the relationships between the dependent variables and the exposures were checked using multivariate logistic regression. Data analysis was performed with Stata 15 and took into account the survey’s sampling design.ResultsThe prevalence of stunting, wasting and underweight was 31.15% (95% CI = 29.90-32.42), 4.79% (95% CI = 4.33–5.31) and 15.82% (95% CI = 14.92–16.76), respectively. The stunting odds were 1.35 (95% CI = 1.15–1.59) and 1.27 (95% CI = 1.01–1.59) times higher for children from households with no water and sanitation services, respectively, compared to children living in households with basic water and sanitation services. Children under five from households with no hygiene facilities and using limited hygiene services had 1.31 (95% CI = 1.05–1.63) and 1.35 (95% CI = 1.10–1.67) times the odds of being stunted, respectively, compared to children covered by basic hygiene facilities. There is no evidence of a significant relationship between household access to WASH and wasting in children under five. The odds of being underweight were 1.33 (95% CI = 1.02–1.72) times higher among children under five from households with limited hygiene facilities than among children from households with basic hygiene facilities.ConclusionInterventions to fight malnutrition in children under five should include a WASH dimension.