Activity of N-acetyl-beta-D-glucosaminidase, beta-glucuronidase, and acid phosphatase and myeloperoxidase was determined in neutrophils and lymphocytes of patients with cancer of the larynx and precancerous states of the larynx as well as--for comparative reasons--in patients with malignant tumors of female generation organs, breast carcinoma, cancer of the stomach and endometriosis. The main result of investigations performed was in fact that intracellular deficiency of beta-glucuronidase within the neutrophils characterizes patients with cancer and precancerous states of the larynx. Patients with cancer of the larynx show additionally a deficiency of neutrophil myeloperoxidase. Deficiency of N-acetyl-beta-D-glucosaminidase occurs, in contrast, in patients with malignancies of female generation organ. Activity of myeloperoxidase in neutrophils from patients with gastric carcinoma is slightly elevated.