OBJECTIVES: To identify the effect of BMI on endogenous biomarkers i.e. cystatin C and creatinine among elderly CKD patients. METHODS: Four groups of participants were selected for this purpose on the basis of Body mass index (Normal, overweight, obese and underweight). Serum cystatin C and creatinine was determined by ELIZA and Jaffe Method respectively. A validated data collection form was developed to record patient demographics and relevant clinical data. Statistical analysis was performed via SPSS version 22. RESULTS: A total of 300 participants were included in the study at the Hospital University Sains Malaysia (HUSM), Kelantan Malaysia, in which majority of the study subjects were females 169 (56.3%). Mean age of patients was 67.6 + 6.7 years. Most of the male (64.6%) and (35.4%) female patients were aged 70-79 years. Mean body mass index (BMI) of the patients was 26 + 5.7 kg/mCONCLUSIONS: Cystatin C can be used in place of creatinine to correctly identify the staging of elderly CKD patients as it is not affected by BMI level as compared to creatinine.