Background: Obesity and overweight are strong independent risk factors for chronic kidney disease (CKD). Using serum creatinine-based estimated glomerular filtration rate (eGFR) equations in these subjects may be inaccurate. On the other hand, cystatin C–based eGFR equations may overestimate CKD prevalence as recent findings suggest an association of cystatin C with obesity. The objective of this study was to assess the accuracy of a cystatin C–based eGFR equation compared to two creatinine –based eGFR equations in overweight and obese subjects. Methods: This was a prospective cross-sectional study which recruited healthy volunteers aged 18-55 years with a body mass index (BMI) ≥ 23kg/m² (Asia Pacific Guidelines). Their renal profiles, serum cystatin C and 99m technetium diethylene triamine pentacetic acid (⁹⁹mTc-DTPA) scans were performed on the same day. The correlations and accuracy of the creatinine-based and cystatin C-based eGFR equations with the ⁹⁹mTc-DTPA GFR were determined. Results: One hundred and one subjects with a median age of 30.0 (27.0-43.5) years and mean BMI of 28.7 ± 4.5 kg/m2 were recruited. The cystatin C-based eGFR equation showed the best correlation with the ⁹⁹mTc-DTPA GFR (r=0.526, p=0.001) and was more accurate in measuring abnormal GFR compared to the creatinine-based eGFR equations. Conclusion: Our study showed that the cystatin C-based eGFR equation was more accurate, sensitive and specific in overweight and obese subjects compared to the creatininebased eGFR equations.