BACKGROUND: Undernutrition is one of the major public health concerns in Bangladesh. This study examined the trends and patterns of childhood undernutrition, inequality, and its socioeconomic contributors in Bangladesh. METHODS: Data were extracted from the last four rounds of the Bangladesh Demographic Health Survey (BDHS). A regression-based decomposition method was applied to assess the socioeconomic contributors of inequality. RESULTS: Although the prevalence of childhood undernutrition has declined during the period 2004 to 2014, the rate of undernutrition is higher among the children of mothers who had lower education, live in rural areas, and are from the poorest wealth quintile. Socioeconomic status accounted for almost half of the total inequality in the prevalence of both stunting and underweight among children, whereas maternal education was ranked second among the contributors. CONCLUSIONS: Findings of the study indicate that undernutrition inequalities in terms of socioeconomic aspects appear to have widened over time. Improving economic activity and maternal education will improve the nutritional status of children and as a consequence reduce inequality. Therefore, investments in education, creation of working opportunities, and empowerment of vulnerable and disadvantaged people along with nutrition-specific interventions will be important measures to eliminate this inequality at the population level.