BACKGROUND: Calprotectin is a cytosolic component of neutrophils. Fecal calprotectin (FC) level is a useful marker for exacerbation of inflammatory bowel disease in children. FC may be a useful marker for necrotizing enterocolitis (NEC). OBJECTIVE: To determine normal baseline levels of FC and observe dynamic changes of FC levels over the first postnatal month in very low birth weight (VLBW) infants. METHODS: FC levels of 14 VLBW infants (gestational age 23-30 weeks, birth weight 350 microg/g stool was noted with signs of gastrointestinal injury, such as bloody stool and bowel perforation. FC levels decreased after initiation of treatments in sick infants who recovered. CONCLUSIONS: FC levels may be a marker for early diagnosis and resolution of gastrointestinal illnesses in VLBW infants. Its utility for early diagnosis and assessment of resolution of NEC should be studied in a larger cohort of VLBW infants.