Abstract We measured urinary excretion of L-type fatty acid binding protein (L-FABP) in preterm neonates on days 1, 5–10, and 25–30 of life. Urinary L-FABP levels (expressed as the ratio to creatinine) in preterm neonates were considerably higher than those of healthy adults. They did not change significantly during the study period. Urinary L-FABP levels showed significant positive correlation with those of urinary N-acetyl-beta- d-glucosaminidase activity on day 1, and with those of 8-hydroxy-2′-deoxyguanosine on days 25–30. These results suggest that L-FABP is expressed in the neonatal kidney. Our results may also point to potential effects of proximal tubular damage and oxidative stress on urinary excretion of L-FABP.