The Healthy Lifestyle-Diet Index (HLD-index), previously developed to assess the degree of adherence to dietary and lifestyle guidelines for primary schoolchildren, was revised according to updated recommendations. Τhe association of the revised HLD-index (R-HLD-index) with obesity and iron deficiency (ID) was also examined.A representative sample of 2660 primary schoolchildren from Greece (9-13 years old) participating in the 'Healthy Growth Study' was examined. Twelve components related to dietary and lifestyle patterns were used to develop the R-HLD-index. Scores from 0 up to 4 were assigned to each one of these components, giving a total score ranging from 0 to 48. The associations between the R-HLD-index, obesity and ID were examined via logistic regression analysis.The total score of the R-HLD-index calculated for each one of the study participants was found to range between 2 and 32 units, with higher scores being indicative of a healthier lifestyle and better diet quality. After adjusting for potential confounders, logistic regression analysis showed that an increase in the R-HLD-index score by one unit was associated with 6% lower odds for obesity. However, no significant association was observed between the R-HLD-index score and ID.The R-HLD-index may be a useful tool for public health policy makers and healthcare professionals when assessing diet quality and lifestyle patterns of primary schoolchildren. Identification of children with lower scores in the R-HLD-index and its individual components could guide tailored made interventions targeting specific children and behaviors.