The glomerular filtration rate (GFR) is the best global indicator of renal function in health and illness. It decreases early in renal disease before onset of renal failure (1). Serum cystatin C has been introduced as a superior and sensitive endogenous marker of GFR. However, there are conflicting reports regarding its use in pregnancy and pre-eclampsia. Sudanese women who develop pre-eclampsia and subsequently eclampsia is still high and a genuine concern. The main target organ is the kidney as glomerular endotheliosis (2). The aim of this study was to assess GFR changes and evaluate the use of serum cystatin C in pre-eclampsia. This is a cross-sectional, case-control and hospital-based study performed in the period from December 2008 to December 2010 in Omdurman Maternity Hospital. The study group was 81 pre-eclamptic compared to100 second half normal pregnant and 65 non-pregnant Sudanese women. A blood sample and a 24-hour urine were collected. Serum cystatin C was determined using latex particle-enhanced immunoturbidimetry with Dako cystatin C PET Kit (3), serum creatinine by Jaffe method and uric acid by Fossati enzymatic reaction at St. Helier Hospital London. Kruskal Wallis test was used for comparisons of means. The mean ± S.E of serum cystatin C for the pre-eclamptic, normal pregnant and non-pregnant were 1.31 mg/L ±0.04, 1.0 mg/L ±0.03 and 0.80 mg/L± 0.01 respectively (P=0.0001). GFR of the pre-eclamptic 66.71 ml/min/1.73 m2 ± 3/09 was significantly lower than that of normal pregnant 89.54 ml/min/1.73 m2 ±2.74 and that of the non-pregnant 86.85 ml/min/1.73 m2 ± 3.31 (P=0.0001). There was no significant correlation of mean GFR of pre-eclamptic cases neither with serum cystatin C (r= -0.16, P=0.25) nor with serum uric acid (r=-0.19, P =0.16), but negatively significant with serum creatinine (r= -0.37, P=0.004) using Spearman’s correlation. The correlation of mean GFR of normal pregnant group was negatively significant with serum cystatin C (r= -0.26, P=0.02), serum creatinine ( r= -0.31, P=0.003 ) and serum uric acid ( r= -0.35, P=0.001). The correlation of mean GFR of the non-pregnant group did not correlate neither with serum cystatin C (r= -0.19, P=0.17) nor with serum creatinine (r= -0.05, P=0.73) or serum uric acid (r= -0.10, P=0.45). The diagnostic accuracy of serum cystatin C level showed it to be sensitive to detect pre-eclampsia at cut-off value equals 1.0 mg/L and specific for pre-eclampsia at cut-off value above 1.0 mg/L for cystatin C. The diagnostic accuracy of serum cystatin C tested using ROC-plot at different cut-off values of GFR found to be not a reliable test for GFR changes in pre-eclampsia. Serum cystatin C may be a useful indicator of pre-eclampsia but not a reliable marker of GFR changes in pre-eclampsia.