Objectives: There is no literature available on the performance ofcystatin C in Chronic Kidney Disease (CKD) patients of Indianpopulation based on age group. Hence, this study is aimed tocompare the diagnostic performance of serum cystatin C andcreatinine with measured glomerular filtration rate (GFR) andestimated GFR (eGFR) in subjects of Indian origin. Methods: The study was carried out at Tiruchirappalli, SouthIndia during the period of September 2010 to march 2011. Onehundred and six CKD patients (82 males, 24 females) wereenrolled and categorized into three groups based on age. The eGFRwas calculated using Cockcroft-Gault (CG) and Modification ofDiet in Renal Disease (MDRD) formulae. Serum cystatin C wasmeasured with a particle-enhanced nephelometric immunoassay(PENIA) method. GFR was measured using 99mTC - diethylenetriamine penta aceticacid (DTPA) renal scan method. Results: Serum cystatin C showed significant correlation withmeasured GFR in all the three groups (r=-0.9735, r=-0.8975 andr=-0.7994 respectively) than serum creatinine (r=-0.7380, r=-0.6852 and r=-0.5127 respectively). Conclusion: Serum cystatin C showed a high correlation withmeasured GFR in young and older patients with CKD thancreatinine. Thus, cystatin C is a good alternative marker tocreatinine in CKD patients.