Chemotaxis of circulating peripheral neutrophils was studied in 12 patients undergoing elective cardiac surgery. Tests of neutrophil chemotaxis were made preoperatively and 16-20 hours postoperatively, using a multipore filter assay. Statistically significant postoperative decrease was demonstrated in both stimulated and random neutrophil migration (p = 0.012 and p = 0.009, respectively). Although the peripheral neutrophil count showed a statistically significant postoperative increase (p = 0.001), the increase did not correlate to the decrease in neutrophil chemotaxis. Nor could correlation be demonstrated between the altered neutrophil chemotaxis and any per- or postoperative variables.