In 49 prematures (25 infected and 24 healthy) serum cholesterol and triglycerides concentrations, value of alpha, pre-beta and beta serum lipoproteins (by electrophoresis) and activity of AspAt, AlAt and GGTP were estimated. It was stated, that the mean serum cholesterol concentration at the beginning of infection was significantly lower than in healthy babies, but in 2-3 week of disease the mean value of this parameter was significantly higher than in first week of life. Mean value of alpha lipoprotein was significantly lower, mean value of pre-beta and beta lipoproteins were higher in sick prematures than in control. In septic prematures positive correlation between the high serum cholesterol concentration and activity of GGTP and AspAt was found. In 30% of all septic neonates hepatitis and in 65% of dead infected prematures structural damage of liver were noted.