AIM:The specific aim of the study was to determine the correlation between the severity of pathology, the amount of blood removed for diagnostic purposes in the 1st week of life and the incidence of early anaemia in very low birth weight (VLBW) infants. METHODS:We recorded the level of haemoglobin (Hb) and haematocrit (Ht) in each of the 50 infants entered in the study at their admission in our neonatal intensive care unit (NICU) and at the age of 8 days. We quantified for each infant the blood drawn for clinical purpose during the 1(st)week of life, using microanalytic techniques for all types of analysis performed. Using the neonatal therapeutic intensive score system (NTISS) we divided all patients into 2 groups: group A= mild light pathology; group B= severe pathology. RESULTS:There was statistically significant difference between the percent decrease of Hb and Ht with reference to the birth weight in the 2 groups. Logistic regression analysis indicated a strong correlation (P = 0.009) between higher degree of illness severity and higher percent decrease of Hb and Ht. The difference due to the amount of phlebotomy losses was not significant. CONCLUSIONS:To our knowledge, this study is the first that strongly suggest that phlebotomy losses is not the main cause of anaemia in VLBW preterm infants in the 1st week of life, when a policy of strictly attention to the amount of blood removed is performed.