The adherence and aggregation abilities of neutrophils (PMNs) were evaluated in thirty three patients with unstable angina, who were qualified for PTCA procedure. The control group consisted of forty one clinically healthy persons. The blood for investigations was obtained from coronary sinus and basilic vein just before the procedure, while in the control group from basilic vein only. The adherence of PMNs to plastic surface (rest and stimulated by PMA) was estimated in vitro according to Oez's et al. method by measuring optical density of generated formazan, whereas the aggregation of PMNs was evaluated using the leukergy test according to the method of Fleck in Berliner's and Aronson's modification. In patients with unstable angina statistically significant higher (p < 0.001) adherence of peripheral blood PMNs, compared with control groups was found (patients: rest-0.525 +/- 0.245, stimulated-0.839 +/- 0.419, control group: rest-0.260 +/- 0.129, stimulated-0.522 +/- 0.377). The aggregation of peripheral blood PMNs was significantly higher (p < 0.05) in the sick than in the control group (the sick-10.98 +/- 4.29%, controls-4.65 +/- 3.01%). No differences in investigated parameters of PMNs obtained from peripheral or coronary sinus blood were found.