Introduction: Transforming growth factor (TGF)-beta is one of numerous inhibitory factors produced by cancer cells that regulate antitumor immunity. The aim of this study was to evaluate TGF-beta1 levels and lymphocyte subsets in the broncholaveolar lavage fluid (BALF) of patients with primary lung cancer and to analyze the interdependence of these parameters. Materials and Methods: BALF samples were collected from 38 patients with primary lung cancer prior to treatment and from 23 healthy volunteers. Concentrations of TGF-beta1 were measured in two independent lots of samples using a commercially available sandwich ELISA kit after concentration of the supernatants. Differential cell counts in the BALF were performed on slides stained with the May Grnwald Giemsa method. Flow cytometry with monoclonal antibodies was applied for lymphocyte phenotyping. Results: A higher level of TGF-beta1 in the BALF of patients compared with the healthy subjects was observed in both lots of samples (3.232.96 pg/ml vs. 1.050.95 pg/ml, p<0.05, and 16.119.3 pg/ml vs. 10.111.1 pg/m,, respectively, difference not significant). There was significant positive correlation of the TGF-beta1 level with the proportion of lymphocytes and negative correlation with both the proportion of macrophages and the percentage of cytotoxic and activated T lymphocytes. Conclusions: Our findings confirmed that TGF-beta takes part in the local response in the course of primary lung cancer.