The objective of this study was to analyze the usefulness anddiagnostic value of the serum cystatin C, PRA and RI in detection ofearly deterioration of renal function in cirrhotic patients.This study was conducted on forty-one cirrhotic patients withnormal serum creatinine <1.5mg/dl. general examination and fullLaboratory investigations including S. creatinine, adjusted creatinineclearance, Plasma Renin Activity, 24-h urine protein and S. cystatin C,Color-coded duplex study were done to assess renal resistive index(RI).Comparing the whole 41 cirrhotic patients to control group, serumcreatinine, PRA, cystatin C and RI were significantly higher in cirrhoticsin comparison to controls. Correlation study as regards the differentparameters within the whole 41 cirrhotic patients revealed that serumcystatin C (r=0.90), serum creatinine (r=0.459), PRA (r=0.702) andRI(r=0.768); all were significantly correlated with adj.Cr.Cl. (Which isthe most widely used parameter for monitoring renal function inhospitalized patients) but serum cystatin C was detected to be thestrongest one correlated to adj.Cr.Cl Cl.At cut off concentrations of 1.63 mg/l for cystatin C ,0.93 mg/dlfor serum creatinine ,6.65 ng/ml/hr for PRA and 0.63 for RI ,serumcystatin C exhibited significantly higher sensitivity and specificity thanserum creatinine , PRA and RI (sensitivity 100% ,specificity 100% forcystatin C and 92.9 % , 92.3% for PRA & 85.7 % ,100% for RI) P<0.05.Logistic regression was done to show significant prediction for liverdecompansation and it was found that cystatin C ,PRA and RI weresignificantly predictors of degree of decompansation of the liver but thehighest( strongest ) was with cystatin C (Odd ratio of regression=10.903)followed by RI (Odd ratio of regression=4.057) then PRA (Odd ratio ofregression =1.989).Conclusion: Cystatin C was the most sensitive marker of earlyimpairment of renal function in cirrhotic patients and exhibitedsignificantly higher sensitivity and specificity than serum creatinine, PRAand RI. From the ROC curve it was clear that cystatin C was superior fordiagnosis of early decrease in creatinine clearance below 80ml/minfollowed by RI then PRA and lastly serum creatinine. Cystatin C was alsothe strongest one correlated with disease severity and cirrhosisdecompansation