Patients with chronic alcoholism (PCA) of stage II have increased glutathione reductase (GR) activity in neutrophils, lymphocytes and monocytes compared with that in the cells of healthy donors, but superoxide dismutase (SOD) activity was high in neutrophils and low in lymphocytes and monocytes. One-h incubation of the cells with indomethacin (10(-7) M-10(-3) M) in vitro has shown that the drug does not abolish the effect of ethanol: at all concentrations used it stimulated SOD in neutrophils but in a dose-dependent manner inhibited it in lymphocytes with the maximum at a 10(-3) M concentration compared to the control. The same concentration of indomethacin stimulated GR activity in neutrophils but inhibited it in lymphocytes and especially in monocytes. A conclusion is made that prostaglandins and leukotrienes an regulate antioxidant enzyme activities in the cells of the immunophagocytic system of PCA, and the mononuclear cells are more sensitive to ethanol treatment than neutrophils.