All newborn infants consecutively admitted to the Neonatal Intensive Care Unit (NICU) at the University Hospital of Trondheim during 1993 were eligible to participate in the study. In total, 241 neonates were included, for whom anamnestic, clinical and laboratory characteristics were recorded. Peripheral blood was retrieved at admittance, and serum levels of soluble intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin were determined. Newborn infants were classified as infected or non-infected according to selected criteria, and 24 newborn infants fulfilled the criteria of having an infection, whereas 168 newborn infants were classified as non-infected. ICAM-1, VCAM-1 and E-selectin were detected in all neonatal samples. Serum concentrations of E-selectin varied by gestational age (GA), higher levels were found in non-infected term (GA > or = 37 weeks) neonates (n = 53) than in those (n = 115) delivered prematurely (GA < 37 weeks) without infection (p < 0.0001), whereas ICAM-1 and VCAM-1 concentrations did not differ between groups of non-infected term and preterm newborn infants. Similarly, newborn infants delivered at term (n = 16) demonstrated higher levels of E-selectin than premature infants (n = 8) in association with infection (p < 0.001). Both ICAM-1 and E-selectin were increased in term newborn infants with infection (n = 16) compared to the non-infected term group (n = 53) (both p < 0.01), whereas VCAM-1 concentrations did not differ between the two groups. In the premature groups of infected (n = 8) and non-infected (n = 115) neonates, no differences in ICAM-1, VCAM-1 and E-selectin concentrations were observed. The use of ICAM-1 concentration (cut-off level: 250 micrograms l-1) as a diagnostic test for infection in term neonates yielded a sensitivity of 80% and a specificity of 61%, whereas a sensitivity of 70% and a specificity of 79% were found when E-selectin concentration (cut-off level: 150 micrograms l-1) was used. Conclusively, increased shedding of soluble ICAM-1 and E-selectin is one component of infection-induced neonatal immune response after full-time pregnancies. Our data suggest that the ability of increased shedding of soluble ICAM-1 and E-selectin molecules is developed during the final weeks of pregnancy. Assessment of ICAM-1 and E-selectin concentrations may be used as diagnostic tools with a high sensitivity and a moderate specificity in term neonates suspected of infection.