Residual renal function (RRF) contributes to dialysis adequacy as well as lower mortality and morbidity in dialysis patients. Even very small changes in glomerular filtration rate (GFR) account for considerable improvements in complications of dialysis. The purpose of this cross-sectional study is to determine the possible contribution of RRF to hemodialysis clearance and to compare the biochemical markers of this patient group with anuric patients. Ten patients with RRF on chronic hemodialysis for more than 6 months were enrolled in the study. Duration of dialysis was not different between the two patient populations. Average GFR was 3.4+/-2.6 ml/min in the group with RRF. Cholesterol, albumin, and triglyceride levels were not different between the groups. Residual renal urea clearance enhanced mean Kt/V of patients from 1.29 to 1.52. However erythropoietin and renin levels were higher in the group with RRF (P=0.019, P=0.044, respectively). There was a positive correlation between erythropoietin, renin levels, and average GFR of all patients (r=0.69, P=0.002, r=0.60, P=0.014). We conclude that RRF plays a greater role in pediatric patients on hemodialysis than previously recognized, and knowledge about patients' RRF should assist in improved overall management.