The complexity of the human diet has instigated researchers to look for a more adequate way to qualitatively and quantitatively assess food consumption and nutrient adequacy, and to relate diet to health. The objective of this study was to assess the diet quality through the Healthy Eating Index (HEI) of 35 preschool children attending a non-profit day care center on Paquetá Island (state of Rio de Janeiro, Brazil) at the moment of enrolling and after six-month by comparing food consumption during weekdays and on the weekend. The dietary assessment was obtained by food history (at the moment of enrolling) using weighed food record method complementing it with information about nutrition at home (after the children's six-month attendance in the day care center) and by food records (on the weekend at home). Later, HEI was determined at the two time points. After the children's six-month attendance in the day care center the mean HEI showed that diet quality was good (score of 88.8). At the moment of enrolling and on weekends, the diet quality needed improvement. Despite the improvement of the diet quality during weekdays, this study demonstrated that the healthful dietary habits are not carried into the weekend at home