10 patients with anal or rectal cancers were given liquid nitrogen cryogenic treatment. In 5 cases the treatment was given prior to abdominoperineal amputation of the rectum. The remaining 5 inoperable cases were given the cryogenic treatment alone, followed, in 3 cases by derivative colostomy. Histological reports on the removed tissues, carried out at different times after the cryogenic treatment, showed the effects of the treatment on the neoplasias and the surrounding tissues and showed the histological equivalent of possible local immunological processes. The thrombosis in the surrounding blood vessels appears to indicate the efficacity of cryogenic therapy in preventing the metastasis of neoplastic cells.