In 30 patients with cancer of the larynx, aged 40 to 70 years, treated by radiotherapy 6 to 9 years ago the decreased activity of neutrophil beta-glucuronidase and N-acetyl-beta-glucosaminidase accompanied by a decrease of absolute count of enzyme-positive cells was noted. Numbers of acid phosphatase-positive neutrophils were also decreased. Moderate increase of the neutrophil alkaline phosphatase activity and of numbers of enzyme-positive cells was another observed feature. The main finding in lymphocytes of the patients consisted in the appearance of cells exhibiting diffusion of lysosomal enzymes, especially of beta-glucuronidase, N-acetyl-beta-glucosaminidase and to a lesser degree of acid phosphatase into the cell cytoplasm. Moderate increase of immunoglobulin level, especially that of IgA, reflected probably the immunologic mobilization of patients.