Introduction: Gastric problems can also impair psychological development and negatively influence the environment and leisure time. The self-instructional module on prevention of gastritis among adolescence helps to improve and update the knowledge regarding healthy lifestyle practices. Objective: To evaluate the effectiveness of the self-learning module on knowledge regarding prevention and management of gastritis among adolescents. Methods: Non-convenience sampling technique was used to collect data from teenagers by providing structure multiple-choice questionnaires. The self-learning module was arranged for the involvement of gastritis in samples. Seven days were provided to the samples for utilising self-learning module which was organised for 45-50 minutes through self-learning, discussion and planned Audio-Visual (AV) aids. Post-test information was gathered after seven days from the day of the learning intervention. Seven days was assigned after getting expert opinions as well as to give time for the implication of knowledge through the practice of prevention and management of gastritis. Chi-square test was also used to find out the association between knowledge of adolescents regarding the prevention and management of gastritis and selected demographic variables. Results: The mean pre-test knowledge score was 8.32 and mean post-test knowledge score was 21.90. There was a statistically significant improvement in the level of knowledge regarding prevention and management of gastritis among adolescents (t0.001, 99=1.98). There was a significant association of knowledge score concerning the education of adolescent and education of father. There was no significant association of knowledge score concerning age, gender, education of mother and area of residence. Conclusion: The post-test knowledge score improved than the pre-test knowledge score. So the self-instructional module has proved to improve adolescents knowledge regarding prevention of gastritis.