Complex immunologic studies using 1 and 2 level tests in 221 individuals (171 workers of raw material processing shops and 50 volunteers) revealed the similar changes in immunologic status of people suffering from byssinosis and workers of long length of service: decreased T-lymphocyte level (owing to T-helpers), phagocyte count and increased serum IgA, IgM in comparison with healthy people. Depressed phagocytosis in 79.6% of people facing byssinosis and 71% of workers with the long length of service can be caused by Gram negative bacteria, contaminating the air of industrial premises. Workers with the short length of service showed increased T-cells level (owing to T-suppressors) and lowered serum IgA, which can be considered as a primary immune response to the dust.