The anti-inflammatory actvity of desoxyribonuclease has been demonstrated on a number of occasions. It has been suggested that its particular features may mean that it possesses an antineoplastic action, especially if employed in asociation with radiation or chemotherapy. The drug, which depolymerises DNA, was administered for 15-60 days [ 1 million U. on alternate days] over a period of 1 yr. in a series of 99 patients, with or without radiation or chemotherapy. No evidence of its antineoplastic activity was obtained, though the anti-inflammatory effect was distinctly observed. Quickly reversible signs of intolerance were noted in about 4% of the series.