ABSTRACT\n\nOBJECTIVE: To assess the effect of using stunting versus underweight as the indicator of child undernutrition for determining whether countries in Latin America and the Caribbean are on track to meet the component of Millennium Development Goal (MDG) 1 pertaining to the eradication of hunger, namely to reduce undernutrition by half between 1990 and 2015.\nMETHODS: The prevalence of underweight and stunting among children less than 5 years of age was calculated for 13 countries in Latin America and the Caribbean by applying the WHO Child Growth Standards to nationally-representative, publicly available anthropometric data. The predicted trend (based on the trend in previous years) and the target trend (based on MDG 1) for stunting and underweight were estimated using linear regression.\nFINDINGS: The choice of indicator affects the conclusions regarding which countries are on track to reach MDG 1. All countries are on track when underweight is used to assess progress towards the target prevalence, but only 6 of them are on track when stunting is used instead. Another two countries come within 2 percentage points of the target prevalence of stunting.\nCONCLUSION: Whether countries are determined to be on track to meet the nutritional component of MDG 1 or not depends on the choice of stunting versus underweight as the indicator. Unfortunately, underweight is the indicator officially used to monitor progress towards MDG 1. In Latin America and the Caribbean, the use of underweight for this purpose will fail to take account of the large remaining burden of stunting.