Background: Adolescence girls who are known about diet are more likely to avoid osteoporosis at menopause. Osteoporosis is a bone disease in which bone loss occurs, so that bones become weak and more likely to break. The aim of this study was to assess the effect of educational program on adolescent girl's awareness regarding balanced diet in the prevention of postmenopausal osteoporosis. Setting: This study was conducted at secondary nursing school in Benha Teaching Hospital. Two tools were used: I:A structured interviewing questionnaire to assess; a) socio-demographic data of the adolescent girls, b) knowledge of adolescent girl's regarding healthy balanced diet, c) knowledge of adolescent girl's regarding osteoporosis, d ) knowledge of adolescent girl's regarding relationship between un balanced diet and osteoporosis at menopause. II: Likert scale to assess attitude of adolescent girls regarding balanced diet. Results: There was highly statistically significant difference pre and post program implementation regarding total knowledge about balanced diet , total knowledge about osteoporosis  and total knowledge about relation between un balanced diet and osteoporosis  (P≤ 0.001) also , there was highly statistically significance correlation between total knowledge score and total attitude score  (P= 0.000) post program implementation while there was no statistical significance correlation preprogram implementation. Conclusion: There was highly statistically significance correlation between total knowledge score and total attitude score (P= 0.000) post program implementation while there was no statistical significance correlation preprogram implementation .Therefore, the study hypothesis was supported. Recommendations: Educational curriculum should include topics of puberty and balanced diet that enable teachers to discuss these subjects with their students and continuous health education program for adolescence must be conducted at school to improve knowledge and attitude of adolescence toward balanced diet.