A reliable method for the determination of renal function in pediatric patients is crucial for the planning of therapy and the administration of therapeutic agents in a variety of conditions. Inulin clearance, the gold standard for the measurement of glomerular filtration rate, is cumbersome and expensive; moreover, inulin is no longer available for clinical use in the USA. The articles reviewed herein reflect the search for simpler laboratory methods suitable for clinical use, new markers of glomerular and tubular function, and more accurate predictors of renal outcome in infants diagnosed prenatally to have urinary tract obstruction.