In a group of 60 patients with surgically treated laryngeal carcinoma blood lymphocyte subsets were assessed on the day of surgery (day 0) and six weeks thereafter by means of flow cytometry. Blood cells at day 0 were also compared to tumor infiltrating lymphocytes (TIL) isolated from surgical specimens. Significant alterations were found in postoperative period as compared to day 0 manifested by the fall of B cells, increase of activated T lymphocytes and NK cells. There were also marked changes between blood cells at day 0 and TIL, evidence in rise of B cells, of activated T lymphocytes and decline of NK cells within the latter. These data suggest that the assessment of lymphocyte subsets may be of value in immunological monitoring of laryngeal carcinoma patients.