This study examines the relationship between early childhood morbidity and young adult health in a poor developing country with a high prevalence of childhood diseases. I take advantage of the rich observational data collected by the Institute of Nutrition of Central America and Panama (INCAP) Longitudinal Study in Guatemala to estimate the effects of five types of childhood illnesses on metabolic syndrome in young adulthood, a predictor of cardiovascular disease and type 2 diabetes. This analysis supports the hypothesis that poor health in childhood is associated with a higher probability of metabolic syndrome in young adulthood. I also find that adult height, often used as a proxy for childhood conditions, does not capture the effects of childhood morbidity. Thus, studies that include height but no direct measure of childhood morbidity are likely to underestimate the effects of child health on later life outcomes. The results highlight the significance of child health programs that can improve population health over the life course.