Adolescence is one of the most rapid phases of development, constitute 10-19 years of age 1 and contribute to 19.6 % of the Indian population. 2 It is one of the most crucial stages in the life of an individual, metamorphosing from being a child into becoming responsible adults. It establishes a strong foundation for adulthood, which propels one to move in the right direction with a right influence and a lack thereof resulting in disastrous consequences, generating an economically productive but a morally precarious population. Adolescence, a stage of physiological, mental and social transformation which accompanies inquisitiveness, impulsiveness and experimentation, makes them prone for risky health behaviours. These behaviours make them vulnerable to diseases especially sexually transmitted diseases such as AIDS. AIDS caused by HIV stands as a threat to entire mankind stigmatizing those affected and petrifies the rest and has rightly been called a social disease. Although, a vast ABSTRACT Background: Adolescence is a stage of physiological, mental and social transformation which poses a threat for risky health behaviours. Inadequate knowledge, taboos regarding sex education, indulgence in risky behaviour lends the adolescents susceptible to AIDS (Acquired Immuno Deficiency Syndrome). Hence, this study was undertaken with the objective to assess the knowledge and attitude towards HIV/AIDS among Adolescent school children in urban Mysore and to describe the factors influencing the same. Methods: This cross sectional study was conducted among schools and pre-university colleges. A simple random sampling technique was used to select the schools and pre-university college and two classes from each school were selected randomly and all adolescents in the class who were present on the day of the study were included. Information regarding their socio-demographic characteristics, knowledge and attitude regarding HIV/AIDS were obtained using a self-administered, pre-tested, semi-structured questionnaire. The children who were mentally disabled were excluded. Results: Among the 374 adolesecents who participated, textbooks 275 (73.5%) were the most common source of information about HIV/AIDS. Knowledge about modes of transmission was higher than about prevention and control and a majority had a positive attitude towards a relative, a friend, a fellow student and teacher whereas, around 50 % had a negative attitude towards a shopkeeper or a housekeeper affected with HIV (Human Immuno Deficiency Virus). Conclusions: Optimal utilization of mass media to deliver key messages and reinforcement using curriculum content would improve the knowledge about HIV and to bring down the discrimination of people living with HIV among adolescents. Life skill education with HIV awareness should be implemented in schools.