We examined the association between diet costs and diet quality in a sample of children and adolescents using data from the ongoing longitudinal (open cohort) DONALD (Dortmund Nutritional and Anthropometric Longitudinally Designed) study. Children and adolescents aged 4-18 years (255 boys and 239 girls) provided 1100 yearly collected 3-day weighted dietary records. Linear mixed (effects) models were used to analyze the association between diet costs ([euro ;[sol;day, estimated using retail food prices) and the Nutrient Quality Index (NQI) and the Healthy Nutrition Score for Kids and Youth (HuSKY). Analysis were stratified for low-quality records (score<median) and high-quality records (score>median). No significant association was found in the low-quality records, whereas in the high-quality records the association was significantly positive for both scores (HuSKY P=0.016, NQI P<0.0001). In conclusion, a substantial part of our sample could increase their diet quality without a noteworthy increase of expenditure.