Tissue blocks from lung parenchyma in the vicinity of primary lung cancer and regional lymph nodes were collected during surgery from 22 patients. Cryostat sections were assessed for the presence of five immunoglobulin classes by means of immunofluorescence. Imprints made from surfaces of freshly resected tumours were used for indirect immunofluorescent reaction to detect anti-tumour antibodies in the autologous system sera of patients after surgery. Also, sera of 60 lung cancer patients were assessed for IgG, A, M levels. It has been found that the direct vicinity of primary lung cancer and regional lymph nodes was a site of intensive immunoglobulin synthesis in plasma cells, with a predominance of the IgA and IgG classes. Serum anti-tumour antibody was found in 3 cases out of 22. There were significantly elevated serum immunoglobulin levels with predominance of IgA and IgG. Inoperable patients had higher immunoglobulin levels then those who underwent surgery.