Multivariate analyses indicate that both age and sex can modulate examination stress effects on immune factors. Stress lowered eosinophil counts in females but raised them in males. Age modulated stress effects on CD4 and CD8 cells, hemoglobin, and erythrocytes. CD4 decreased more in older subjects; CD8 increased in older and decreased in younger subjects; hemoglobin decreased in younger but not older subjects; erythrocytes increased in older and decreased in younger subjects. Initial age and/or sex differences in levels of neutrophils and lymphocytes were not statistically altered by stress. Stress effects not modulated by age or sex increased serum IgA and IgM, CD19, and stimulated phagocytic activity but decreased serum IgG, CD3, basophils, and unstimulated phagocytic activity. The immunological effects of stress are multiple and are influenced by variations in age and sex of the person.