Food insecurity, the lack of consistent access to sufficient quality and quantity of food, affects an estimated 800 million people around the world. Although household food insecurity is generally associated with poor child nutrition and health in the USA, we know less about household food insecurity and child health in developing countries. Particularly lacking is research assessing how associations between household food insecurity and children's health outcomes may differ by child age and among children beyond age 5years in low-income settings. We use data from a population-based sample of households with children ages 3-11years (N=431) in Leon, Nicaragua to consider how household food insecurity is associated with three measures of child health: illness, anaemia and low height-for-age. Our results provide new evidence that even mild household food insecurity is detrimental to children's health; and that child age conditions the associations between household food insecurity and child health. We find that food insecurity is especially harmful to health during early childhood, but continues to have significant associations with health into middle childhood (up to ages 7-8years). We discuss the potential implications of these results for future child health research and policies in low-income countries. (C) 2016 John Wiley & Sons Ltd