We prospectively determined serum concentrations of soluble intercellular adhesion molecule 1 (sICAM-1) in the first 2 weeks of life in 32 preterm newborns in an attempt to assess whether these concentrations are reliable markers of sepsis in newborns at risk of infection. Ten of the study group were normal and had been hospitalized only for low birth weight. The remaining 22 presented respiratory distress (RDS) and were at even higher risk of infection because they required assisted mechanical ventilation and central venous catheterisation for parenteral feeding and infusion therapy. Sepsis was diagnosed in 11/22 newborns with RDS: in 3 on day 3 and in 8 on day 7. Circulating sICAM-1 concentrations were significantly elevated in neonates with RDS (group II) and associated infection (group III) compared with normal newborns (group I). However, after day 3 of life sICAM-1 values were significantly higher in group III than in group II.