The immunological effects of the environmental and/or occupational exposure to NO₂ and NO in air as polluting gases have been examined in groups of 16 men. The determina-tion of NO₂ and NO concentrations in ambient air in the work enviroment as well as in ambient air in residential areas of these men was performed, always by use of an Amaya-Sugiura passive sampling spectrophotometric method. Mean concentration of NO₂ in ambient air in residential areas was 0.0210 mg x m^-3 (0.0070 to 0.0470). NO₂and NO mean concentrations in ambient air in the work enviroment were 0.0867 mg x m^-3 (0.0165 to 0.1960) and 0.0614 mg x m^-3 (0.0220 to 0.1090) respectively. For the determination of T-cell and (CD19+)B-cells populations Behring monoclonal antibodies were used in indirect immuno-fluores-cence tests. The serum levels of immunoglobulins: G, A, M, E; C3c and C4 complement components; total circulating immunological complexes (CIC) as well as acute phase proteins: C-reactive protein (CRP), haptoglobin, ceruloplasmin and transferrin were determined by nephelometry. Stimulation T-cell line in exposed to NO₂ and NO was evidenced by in-creased number of (CD3+)T-cells, by about twice (p<0.001) increased number of (CD4+)T-helper cells and by increased number of (CD8+)T-suppressor cells. The higher increase in count of (CD4+)T-helper cells than (CD8+)T-suppressor cells population caused the increased value of the (CD+4)T-helper/(CD8+)T-suppressor ratio by about 25% (p<0.01) in the men exposed to NO₂ and NO. No changes were observed in the number of (CD19+)B-cells as well as in the (CD3+)T/(CD8+)T-suppressor ratio. In men of exposed to NO₂ and NO elevation of IgG serum concentration by a 17.7% (p<0.01) was evidenced as well as decreased of C3c by 18.6% (p<0.001) and C4 by 35% (p<0.001), whereas total CIC in serum was elevated by about twice (p<0.001). Significant positive correlations between concentrations of NO₂ in air and numbers of total lymphocytes, (CD3+)-cells, (CD4+)T-helper, (CD8+)T-suppressor cells or IgG (/r/ from 0.31 to 0.71) as well as significant negative correlations between concentrations in air of NO₂ and IgE, C3c, CRP or haptoglobin (/r/ from -0.49 to -0.31) were calculated. Moreover, significant positive correlation between NO concentrations in air in work place and counts of (CD3+)T-, (CD8+)T-suppressor, (CD19+)B-cells and levels in serum of C4, haptoglobin and ceruloplasmin (/r/ from 0.33 to 0.63) as well as significant negative correlations between NO concentrations in air in work place and serum levels of IgG, IgA and IgM (/r/ from -0.67 to -0.47) were also observed. In conclusion, environmental exposure to NO₂ and NO can modificate in the peripheral blood of humans the parameters of cell-mediated and/or humoral immunity.