Background: Food is of no exception; Healthy nutritious foods have been replaced by the new food mantra ‘junk food’. Junk food comprises of anything that is quick, tasty, convenient and fashionable. It seems to have engulfed every age, every race and the newest entrants in children. Varieties of junk foods are Pizza, Burgers, Cakes, Gobi, Butter chicken, chips, Ice creams, Chocolates, French fries and Sandwich, and harmful effects are such as Constipation, Heart attack, Dental problem, Indigestion, Weight gain, Cancer, Pimples, Nutritional deficiency, Fatigue. Methods: In this study, the sample size is 120 adolescents in the age group of 13-15 years of selected English medium high school of Bagalkot. Convenient sampling technique was used for selection of high school in Bagalkot. A disproportionate stratified random sampling was used to select 120 adolescents. Data collection done by Structured knowledge questionnaire on health hazards of junk food and attitude scale on consumption of junk food which developed by researcher. Results: The post-test results showed that (100%) of adolescents having good knowledge and the highest number of adolescents (88%) having unfavorable attitude, there was significant association between adolescent knowledge score with class studying in chi-square value is 6.2, and there was significant association between adolescent’s attitude score with previous information chi-square value is 8.4. Conclusion: After evaluation of knowledge and attitude on adolescents on adverse effects of junk foods among adolescents, it was found that most of adolescents had poor knowledge and unfavorable attitude regarding junk food. Keywords: Attitude, Adolescents, Junk foods, Knowledge.