Iron deficiency anemia is one of the most common problems among adolescentsand  almostoe in  among ten children have this problem. A study was conducted with a sample size of 60 among the adolescents girls in the age group of 13 – 18 yrs studying in matriculation schools, Chennai using Quasi experimental, pre–test and post test control group design. Samples were selected by using stratified random sampling technique.  The tool consisted of the demographic data, structured knowledge questionnaire and Likert’s attitude scale. Reliability was checked by using test retest method using Karl Person’s Formula. (r= 0.981 for knowledge and r= 0.914 for attitude).Pre–test and post test was conducted in both group and structured teaching programme was administered to experimental group. The data was analyzed using descriptive and inferential statistics.   The findings study showed that in control group 16(53.3%) samples were having moderate level of knowledge in pre–test and 20(66.7%) samples were having moderate level of knowledge in post test. In experimental group, 19(63.3%) samples were having inadequate level of knowledge in pre test and whereas 30(100%) samples had adequate level of knowledge in post–test. In experimental group 25 (83.3%) samples were having moderately favorable attitude in pre test and 30 (100%) samples were having favourable attitude in post test. Hence the study concluded that structured teaching programme was effective in improving the knowledge and attitude towards prevention of iron deficiency anemia among adolescent girls.