We estimated the effect of trimetazidine on biological activity of neutrophils in patients with exercise test--induced transient myocardial ischaemia. The study group comprised 16 patients (10 men and 6 women) aged 40-56 years (mean 48.2 years) with stable angina. Exercise test was performed on cycloer-gometer (Medicor, Hungary). Trimetazidine in a dose 3 x 20 mg/day was applied 24 hours prior to the exercise test. The control group consisted of 14 patients (9 men and 5 women) aged 37-59 years (mean 47.9 years), with stable angina, in whom exercise test was performed but the drug was not administered. Blood samples for examination were taken from basilic vein before the exercise test and 10 min afterwards. To evaluate the ability of neutrophils to aggregate the leukergy test of Fleck modified by Berliner and Aronson was applied. Oxidative metabolism of nonstimulated and stimulated by fMLP and PMA was measured using chemiluminescence method. It was shown that in patients with stable angina trimetazidine caused decrease in neutrophil aggregation. The drug did not inhibit neutrophil biological activity af-ter exercise test--induced myocardial ischaemia.