Background: Several studies have attempted to assess the global quality of diet. One of such initiatives is the Healthy Eating index (HEI), developed in the Unites States. However, its application in other countries requires certain adaptations. Aim: To adapt the HEI to the Chilean population and to assess its value in Chilean school age children and adults. Material anal methods: A random sample of 264 school age children aged 13.4 ± 0.7 years and 264 adults aged 35.7 ± 0.6 years was studied. A 24 hours food recall was done and the HEI seas calculated considering 10 variables based in the Feeding Guides for the Chilean population. Feeding habits were classified as healthy when the score was over 80 (of a maximum of 100), as requiring changes when the score was between 51 and 80 and as unhealthy when the score was 50 or less. Results: The mean scores for children and adults were 58.4 ± 11.3 and 56.2 ± 11.1 respectively (p< 0.02). The variables with lower scores were vegetables, fruits, dairy products and sodium. Only 1.5% of the population had healthy feeding habits, without differences by sex or age. Feeding quality was significantly worse among obese subjects. Conclusions: The HEI is a tool that can be used in the Chilean population and can be used to assess the effectiveness of health promotion initiatives. It also can help to focalize educational programs to specific nutrients (Rev Méd Chile 2005; 133: 175-82)