Background: During adolescence, a phase of growth and development requires a lot of macros and micronutrient intake. The physical changes will certainly affect nutritional status, leading to nutritional problems, such as anaemia. Objective: To determine the level of knowledge of adolescent girls about iron supplements and how they use them to overcome anaemia. Method: A descriptive study with a cross-sectional design was used in this research, and an accidental sampling technique was used. Result: Most of the respondents need better knowledge, despite most of them having taken iron supplements from school, which is a part of the programs from the government. Many respondents have received information about iron supplements and anaemia, but numerous still do not comply with taking iron supplements. Conclusion: Education needs to be carried out to increase the compliance of adolescent girls in using iron supplements to improve the quality of the next generation.