Cancer is the second leading cause of mortality and morbidity in both developed and developing countries. In India, cancer prevalence is estimated around 2.5 million, with over 0.8 million new cases and 0.5 million deaths occurring each year. There is an increase in the incidence of breast cancer and found to be gradually overtaking cancer of the cervix.Breast self-examination (BSE) is an important screening measure for detecting breast cancer.There is evidence that women who correctly practice.Breast self-examination monthly are more likely to detect a lump in the early stage of its development, and early diagnosis has been reported to influence early treatment, to yield a better survival rate.Thus the present study aimed at evaluating the effectiveness of structured teaching programme on breast self examination (BSE) among the teachers of Lakshiammal Memorial matriculation higher secondary school, Chrompet, Chennai-44. The purpose of the study is to assess the knowledge among school teacher before and after administering planned teaching programmeregarding breast self examination, to assess the effectiveness of planned teaching program among school teachersregarding breast self examination (BSE) and to associate the post test knowledge score with selected demographic variables of school teachers. The study method was evaluative research approach and a pre experimental one group pre test and post test research design was used. Randomized sampling technique was used to select the sample. The total samplewas 60 school teachers.Pre test and post test scores was assessed by using standardized questionnaires. The result of the study concluded that mean and standard deviation of knowledge level score in pre test was 36.1 and 2.4 and post test score was 70.6 and 5.1. the calculated ‘t’value was 80.2 which reveals that there was statistically highly significant difference between the pre test and post test score. It is evidenced that the planned teaching programme was significantly effective in improving knowledge regarding breast self examination (BSE) among school teachers.