Acute renal failure (ARF) in neonates may occur after renal ischemia. Growth factors participate in the tubular regeneration process. Insulin-like growth factor-1 (IGF-1) is produced in the kidney during the recovery phase of ARF. Tumor necrosis factor-alpha (TNFalpha) may play a role in renal apoptosis. We examined serum and urinary IGF-1 and TNFalpha in neonates with or without ARF after asphyxia, in order to assess their possible use as markers of renal damage and recovery. We studied 20 full-term asphyxiated neonates, 10 with ARF and 10 without ARF, and compared them with 13 normal newborns for 7 days after birth. Blood urea, creatinine, pH, base deficit, and serum and urine IGF-1 and TNFalpha were assessed. Neonates with ARF had more-severe acidosis than patients without ARF. All patients had lower serum IGF-1 values immediately after birth than control children. Serum IGF-1 remained low in the ARF patients. The initial urinary IGF-1 was higher in all patients compared with control newborns, and remained elevated for the rest of the study only in the ARF neonates. Serum and urinary TNFalpha concentrations were similar for all healthy and diseased neonates. Measurement of serum and urinary IGF-1 levels in ARF neonates might be of additional value for clinical assessment of ARF.