10.22376/ijpbs.2019.10.1.p1-12 Volume 2 Issue 1 2011 (January - March) To determine whether serum cystatin C is a better marker of Glomerular Filtration Rate (GFR) when compared with serum creatinine in subjects with chronic kidney disease (CKD).106 patients with chronic kidney disease were enrolled in this study. They were categorized into 4 groups, based on GFR levels. GFR lessThan 15 ml/min/1.73m2 (group1; n = 20), GFR: 16-29 ml/min/1.73m2 (Group 2; n = 36), GFR: 30-59 ml/min/1.73m2 (group 3; n = 38), and GFR: 60-89 ml/min/1.73m2 (group 4; n = 12). In all the groups, cystatin C correlated well with iGFR [P= lessThan 0.0001(group2); P=0.0001(group3); P= 0.0027(group4)] than creatinine (P=0.0019; P= 0.0185; P=0.0272 respectively), but a significant correlation between cystatin C with iGFR (P= 0.0178) was seen, on the other hand no significant correlation between iGFR with creatinine (P = 0.2285) in group 1.Our results showed that serum cystatin C is potentially a better marker for detecting impaired renal function than serum creatinine.  R.KUMARESAN,P.GIRI Glomerular Filtration Rate, chronic kidney disease, 99mTc -DTPA, PENIA, cystatin C, creatinine. 36-40