Maturation of neonatal glomerular function as evidenced by serum creatinine and creatinine clearance was assessed in 15 preterm small for dates infants (Group I) and compared with values obtained in 15 preterm appropriate for date babies (Group II), on 3rd, 7th and 14th postnatal days. The mean gestational ages were 34.2 and 32.5 weeks and birth weights 1436 +/- 302g and 1752 +/- 422 g, respectively. The mean serum creatinine values in Group I were 1.40 +/- 0.28, 1.18 +/- 0.22 and 0.92 +/- 0.11 mg/dl and for Group II, 1.22 +/- 0.22, 1.01 +/- 0.24 and 0.82 +/- 0.17 mg/dl on days 3, 7 and 14, respectively. Glomerular filtration rates as evidenced by creatinine clearance were 16.08 +/- 3.53, 21.25 +/- 4.79 and 36.96 +/- 6.44 ml/min/1.73 m2 for Group I as compared to 21.38 +/- 6.65, 35.96 +/- 11.47 and 57.61 +/- 21.61 ml/min/1.73 m2 for Group II on these days, showing statistically significant (p < 0.001) increase in renal function in both the groups from days 3 to 14. Even though the serum creatinine values in the two groups were comparable at identical postnatal ages, creatinine clearance was shown to be statistically less (p < 0.05 on day 3, p < 0.001 on day 7 and p < 0.01 on day 14, respectively) in Group I as compared to Group II, thereby implying slower renal maturation in small for dates preterm babies.