Substantial variation across states in the prevalence and trends in childhood overweight and obesity indicate a need for state-specific surveillance to make state comparisons to national estimates and identify high-risk populations. The purpose of this study was to examine body mass index (BMI) trends among third-grade children in Ohio between the 2004-2005 and 2009-2010 school years and examine changes in prevalence of obesity by specific demographic subgroups. Third-grade children (n=33,672) were directly weighed and measured throughout the school years by trained health care professionals.