The aim of this study was to evaluate neutrophil chemotaxis and random migration in healthy newborn infants and septic neonates with similar gestational and postnatal age. Possible relationships between chemotactic activity, random migration, causative microorganisms, and clinical course of septic infants were also investigated. The neutrophil chemotaxis and random migration was evaluated in 24 healthy newborn babies and 34 septic neonates and 20 healthy adults by modified Boyden technique. The mean neutrophil chemotaxis of healthy preterm-term infants and adults were similar (66.6 +/- 18.9, 64.4 +/- 19.9, and 74.7 +/- 77 mu m, respectively). The mean neutrophil random migration of healthy term infants was not different than that of adults. But the mean neutrophil random migration of healthy preterm infants was lower than that of adults (36.9 +/- 13.7 and 43.5 +/- 11.8 mu m, respectively) (p = 0.03). The mean neutrophil chemotaxis and random migration septic term infants were not different from the value of healthy term infants (p > 0.05). Although the mean random migration of septic and preterm infants were similar (p > 0.05), the mean neutrophil chemotaxis of septic preterm infants was lower than the value of healthy preterm infants (p = 0.04). Not only mean neutrophil chemotaxis of septic preterm acid term infants were significantly lower than that of adults (p = 0.002 and p = 0.006, respectively) but also neutrophil random migration of septic preterm and term infants were significantly lower than that of adults (p = 0.001 and p = 0.005, respectively). There was no relationship between the nature of causative microorganism and neutrophil random migration or chemotactic activity. Polymorphonuclear leukocytes chemotaxis was significantly lower in preterm with sepsis compared with healthy preterm-term infants and adults. These findings may indicate deterioration in neutrophil functions in premature babies under stress but more detailed studies with larger groups are needed.