The health of people depends on habits 50% and 20% physical environment. AIM: The aim of this study was to evaluate the effectiveness of a Health Intervention Program for the improvement of the nutrition habits among office employees. METHODOLOGY: The sample of the present study consisted from 165 office employees from an Educational Institute and 29 employees were applied for participating in the health intervention program. The interference was based on two theories (a) The Theory of Social Learning and (b) The Theory of Planned Behavior. Additionally, the Employees completed an anonymous questionnaire. RESULTS: Referring to the knowledge it was as follow: The 95% of women was against vegetarian food while men were 80% (p = 0.035). The 95% of women disagreed for vitamins in tablets while men were 88.6% (p = 0.020). Gymnasium graduates had a dichotomous idea comparing to all others education levels concerning the age and the calories (p < 0,001), the body formation and the calories as well the physical activity (p =0,011και p =0,023 corresponding). As the age was up the preference was up as well, for vegetarian lipids instead of animal lipids (p = 0.012), the rejection for white bread instead of whole brown bread (p< 0.001), the often use of alcohol drinks decreased (p = 0.001). The elder people ate rare in fast food comparing to the young people (p = 0.002), they didn't consume hydrogen fat comparing with the younger (p= 0.006). When the results were compared before and after the health intervention program with x2, there did not exist significant differences but the improvement of correct nutritional knowledge and better nutritional habits, were obvious. CONCLUSION: The intervention group presented satisfied, more informed from the implementation of the program, believing that the participation in the program has helped to improve the quality of the food and the nutritional habits.