Cancer patients frequently have detectably depressed immune competence, especially cell-mediated immunity. Number and percentage of total and active form T-lymphocyte in peripheral blood, serum level of IgE and IgA were assessed in patients with head and neck cancer, who were admitted to the Severance Hospital from September 1980 to June 1981 and were with histologically diagnosed malignant tumor in head and neck. Percentage of total T-lymphocyte in patient with head and neck malignancy was 64.8%, slightly lesser than normal control group without statistical significance. Percentage of active form T-lymphocyte in patient with head and neck malignancy was 47.8% and decreased compared with that of normal control significantly(p<0.05). There was no relationship between total number and percentage of T-lymphocyte and stage of malignancy or nodal involvement. Percentage of the active form T-lymphocyte in nodal involvement cases was 44.0% and was decreased compared with that in no nodal involvement cases, but there was no statistical significance. Level of the IgE in serum in patients with head and neck malignancy was increased markedly comparing to that in normal control group. There was tendency of increasement of IgE with the progression of stage. There was no difference in the level of IgA in serum between patients with head and neck malignancy and normal control group, and between the stage of the disease.