Background: The mobile phone is modern technological invention, which has reached all parts of the world enabling speedy telecommunications worldwide. Today there is about 3.5 billion users. The use of mobile phones among young children and adolescent also increasing dramatically likewise the adverse effects of problematic mobile phone usage also increasing enormously. Objectives: The present study aimed to assess the knowledge regarding adverse effects of problematic use of mobile phones among adolescents. Method: The Descriptive survey approach was adopted in this present study. A total 50 adolescent school students were selected by using simple random sampling method. The tool used for data collection was structured knowledge questionnaire. Result: This study result shows that among 50 adolescent students, 30 (60%) students have average knowledge regarding adverse effects of problematic use of mobile phone, 16 (32%) students have good knowledge, 3 (6%) have poor knowledge, only 1 (2%) has very good knowledge and none of them have very poor knowledge regarding adverse effects of problematic use of mobile phone. There was no significant association between the knowledge of the students with the demographic variables such as age, gender, religion, occupation of parents, education of parents, type of family, monthly income etc. Conclusion: This study helps nurse researchers to develop appropriate health education tools for educating the students regarding adverse effects of problematic use of mobile phone at community level and institutional level.