Some authors questioned the prognostic value of indicators of metabolic acidosis (pH, HCO3, BE). On the other hand, the elevated serum lactates are considered to be sensitive markers of anaerobic metabolism in peripheral tissues with significant predictive value. The aim of the study was to analyse the relationship between SNAP index and serum lactates as well as the markers of metabolic acidosis in newborns treated in intensive care unit (ICU). 173 newborns up to the 72 hour of life admitted to the ICU were enrolled into the study. Mean birth weight was 2045 +/- 808 grams, mean gestational age--35 +/- 4 weeks. SNAP (evaluated on the first day of hospitalization) ranged from 0 to 41 points, with the mean value of 9 points. Based on the SNAP, the study group was divided into four subgroups: 0-8 points, 9-16 points, 17-24 points and more than 24 points. Observations were prolonged up to the 48 hour of hospital stay, with at least one measurement of serum lactates, blood gases and calculation of the anion gap. Elevated serum lactates were found even with the SNAP as low as 8 points, but significantly high concentration of lactates was observed in newborns with more than 24 points. Uncompensated metabolic acidosis was found in newborns with more than 9 points in SNAP. Any relationship was found between the SNAP at admission and HCO3 concentration or anion gap. Serum lactates correlated much better with the clinical status of the newborn in comparison to markers of metabolic acidosis (pH, HCO3, BE).