Introduction: Anaemia is a significant public health problem among adolescents globally but there is limited data in many countries, including Malaysia. This study aims to investigate the 5-years incidence of anemia among Malaysian adolescents by gender, ethnicity, locality of schools, Body Mass Index, stature and diet intake. Methods: A secondary analysis of existing data from MyHeART study was conducted within a closed cohort of 528 adolescents (aged 13 years) attended 15 public secondary schools from Kuala Lumpur, Selangor and Perak. The adolescents who were followed up at 15 and 17 years old had completed haemoglobin assessment, anthropometric measurements and -days diet history. The data was cleaned and missingness was handled accordingly with multiple imputation. SPSS Software version 21 was used to analyse the data, with Generalised Estimating Equation (GEE) showing the effect of time on the trajectory of prevalence of anaemia over the 5 years. Results: The prevalence or incidence? of anaemia in 2012, 2014 and 2016 was 7.9% (95%CI: 5.0-12.3), 13.9% (95%CI: 10.0-19.0) and 15.8% (95%CI:11.3-21.7). In females, anaemia increased from 11.1% (95%CI:6.7-18.7) to 15.7% (11.4-21.3) and 23.1%(95%CI: 16.8-31.0); the change was significant from 13 to 15 years old. Similar trend was noticed in those who are stunted, overweight/obese, in both urban/rural schools and didn’t meet their daily recommended nutrient intake for total calorie, protein and iron. Conclusion: Anaemia is increasing in trend among the adolescents over the years and deems attention from the relevant stakeholders to create a robust anemia prevention program.