Serum immunoglobulin IgG, IgA and IgM levels were estimated in 112 patients with bronchogenic carcinoma, and the obtained values were as follows: IgG = 1762 +/- 595 mg/100 ml; IgA = 332 +/- 104 mg/100 ml; IgM = 157 +/- 76 mg/100 ml. Subsequently the patients were divided in a group of 74 patients with epidermoid carcinoma, and a group of 38 patients with small cell anaplastic carcinoma of the bronchus. In patients with epidermoid carcinoma, in cases with disseminated disease the mean survival was shorter (7.9 months) when compared to the mean survival of patients with localized disease (20.8 months). Similarly, a depression of lymphocyte counts was observed in cases with disseminated disease. In cases with IgA concentrations ranging from 300 to 410 mg/100 ml longer survival rates were observed. In patients with small cell anaplastic carcinoma variety, the survival rates in patients with localized disease were almost identical with those in patients with disseminated disease (11.4 months versus 9.9 months). The longest survival rates were observed in cases with IgG concentrations ranging from 1600 to 2100 mg/100 ml, and IgM concentrations ranging from 190 to 320 mg/100 ml of serum.