The study aimed at assessing the pre interventional knowledge score regarding preventive measures of HIV/AIDS among adolescents, before implementation of planned teaching programme (pre-test), assessing the knowledge score regarding preventive measures of HIV/AIDS among adolescents, after implementation of planned teaching programme (post-test), to compare between the pre-test and the post-test level of knowledge regarding preventive measures of HIV/AIDS among adolescents and to determine the association the of Pre-interventional knowledge scores regarding the preventive measures of HIV/AIDS with the selected demographic variables such as, age, standard, religion, fathers occupation, family income, habits, family pattern, previous knowledge, source of media, socioeconomic status. A pre-experimental one group-pre-test pos-test research design was selected. The study was conducted on 60 adolescent students of the St. Georges Higher Secondary School, Bhopal, Madya Pradesh. The sampling technique used was Stratified Random sampling technique. The method of data collection was by the structured knowledge questionnaire. The data collection instruments and teaching plan were established through an extensive review of literature and content validity which provided adequate content area, information, consultation, discussion with experts and based on the experience of the investigators and even personnel experience. The Reliability was established from data of 10 samples by parallel method. Using these values Karl pearsons’ correlation co-efficient was computed and the r value obtained. Result of the study indicate that among 60 adolescents’ regarding the level of knowledge scores of pre and post test reveals that during pre-test 47% of the adolescent group had average knowledge and 53% of the adolescent had poor knowledge regarding prevention of HIV/AIDS. Further, during post-test 30% of the adolescent group had average knowledge and 68% of the adolescent had good knowledge and 2% percent had poor knowledge regarding prevention of HIV/AIDS. The mean pre-test score of adolescents regarding prevention of HIV/AIDS was 9.83, standard deviation was 4.307. The post-interventional mean score of adolescents regarding prevention of HIV/AIDS was 21.65, standard deviation was 21.65. Hence it can be interpreted that structured teaching programme was effective as the level of knowledge of the adolescents’ have increased.