Abstract. OBJECTIVE: Transfusion Associated Necrotizing Enterocolitis (TANEC) is defined as the onset of necrotizing enterocolitis (NEC) within 48 hours of receiving a blood transfusion in preterm neonates. We wanted to determine if hematocrit changes following blood transfusions were associated with disease development. PATIENTS AND METHODS: This is a case-control analysis of inborn neonates ≤32 weeks' gestational age, from January 1, 2007 and December 31, 2010, who were diagnosed with Bell stage II or greater NEC. Those meeting TANEC criteria were identified and an analysis completed to determine if beginning or ending hematocrit values were associated with an increased risk for disease development. RESULTS: Nineteen of forty-nine (39%) infants with NEC met the criteria for TANEC. We found no differences in gestational age at birth or birth weight in our experimental groups. The degree of illness including PDA, IVH, central line use, and respiratory support 48 hours prior to disease onset was also similar between groups. Those with TANEC had higher modified Bell staging of NEC and were more likely to be receiving full enteric feeds at the time of NEC onset. No statistically significant differences were found in hematocrit levels prior to or following the blood transfusion closest to NEC onset in the TANEC group, as compared to classic NEC (CNEC) or control infants. CONCLUSION: The onset of NEC following transfusion occurs with a frequency that invites investigation regarding causation. Our data indicates no association between the beginning and ending hematocrit values and TANEC in our patient population.