Background: Chronic kidney disease (CKD) is an increasingly common disease worldwide and has become a global health problem, especially in Vietnam. Cystatin C is a marker for the detection, classification, and prognosis of CKD. Cystatin C is filtered entirely through the glomerular membrane, reabsorbed, and metabolized completely in the renal tubules. In case of damage to the kidneys, glomerular filtration rate declines, and some substances increase in the blood, such as cystatin C. The concentration of cystatin C changes with damage to the renal system. Objectives: This study aimed to estimate the concentration of cystatin C and its variation in the different stages of CKD. Methods: A descriptive, cross-sectional study was conducted on 40 healthy individuals and 137 patients with CKD grade III, IV, and V in 103 Hospital. The concentration of cystatin C was estimated in all subjects. Results: Cystatin C plasma levels were significantly higher in the CKD group (9.17 ± 3.75 mg/L) than in the control group (0.82 ± 0.12 mg/L). Cystatin C plasma levels increased linearly with the serious kidney failure as the stage of CKD. Conclusions: Cystatin C is an effective marker for estimating kidney damage in CKD.