This study examined the temporal stability of enumerative immune responses to acute psychosocial stress. Lymphocyte subsets were measured in 24 healthy male subjects at rest and following a speaking stressor on two occasions approximately six weeks apart. The speaking task caused significant increases in T-suppressor/cytotoxic cells, natural killer cells, T-cells, and total WBC and decreases in the T-helper/suppressor ratio. Baseline test-retest correlation's were statistically significant for all variables (r values = 0.40-0.90). With two exceptions (T-cells and T-suppressor/cytotoxic cells), speaking task values (absolute reactivity scores) were also statistically significant (r values = 0.48-0.92). Baseline adjusted test-retest correlations were however generally less reliable, with only natural killer cells (r values > 0.40), the T-helper/suppressor ratio (r = 0.60), and total WBC (r = 0.48) showing statistical significance. The findings suggest that certain but not all cellular immune responses to acute stress are moderately stable over time.