The study is carried out to assess the level of knowledge and practice on biodegradable sanitary napkins among adolescent girls, to determine the correlation between the knowledge and practice and to find out the association between the knowledge and practice with the selected demographic variables. There is a significant relationship between the level of knowledge and practice. There is a significant association between the knowledge and practice with selected demographic variables. The quantative and non-experimental descriptive research design was adapted. Purposive sampling technique was used. Results shows that, 22% of them had adequate knowledge, 40% of them had moderate level of knowledge, 38% of them had inadequate knowledge and 16.6% of them had adequate level of practice, 66.6%, of them had moderate level of practice and 16.6% of them had inadequate level of practice. There is a positive correlation between knowledge and practice (r' value= 0.80