Oxidative burst activity and the expression of adhesion molecules have been used as indicators of leukocyte activation status. The aim of the study was to delineate the relationship of oxidative burst activity and the expression of adhesion molecules in neutrophils and monocytes from a pool of healthy volunteers (n = 96). We also tested the potential role of gender and a racial background in the individual response differences. Basal and phorbol myristate acetate (PMA)‐stimulated oxidative burst and CD11b expression were determined using dihydrorhodamine 123 and phycoerythrin (PE)‐conjugated anti‐CD11b monoclonal antibodies. PMA markedly increased CD11b expression and cellular oxidant content in neutrophils and monocytes in all samples. However, the responses showed considerable variability among individuals. A positive correlation was observed between the responsiveness of neutrophils and monocytes in their basal or PMA‐stimulated CD11b expressions and PMA‐stimulated oxidative burst activities. In contrast, no correlation was found between the level of adhesion molecule expression and cellular oxidant content in monocytes or neutrophils either under basal or under PMA‐stimulated conditions. The reactivity of oxidative burst (i.e., PMA‐stimulated over basal) was significantly lower in neutrophils from African American males compared with cells from African American females, white females, or white males. In contrast, reactivity of monocytes was significantly elevated in white males compared with all other groups. These findings indicate that leukocytes with a relatively high degree of adhesion molecule expression may display an average or decreased oxidative burst activity, and vice versa. Our findings also indicate that ethnic background may influence the oxidative burst activity in neutrophils and monocytes. This needs consideration in clinical studies utilizing healthy volunteers with mixed gender and ethnic backgrounds. Cytometry (Comm. Clin. Cytometry) 46:243–246, 2001. © 2001 Wiley‐Liss, Inc.