The range of application of cryosurgical techniques to the treatment of cancer is widely diversified and slowly increasing in scope. From these, one may reach the general conclusion that cryosurgical techniques are a standard method of treatment, competitive with other methods of therapy, in cancer located in some sites. For cancers located in other sites, cryosurgery is only useful as an end resort in selected patients. In some areas, especially in the viscera, cryosurgical techniques are only in developmental stages. Cryosurgery is most useful in easily accessible areas of the body. The results of the treatment of most carcinomas of the skin with cryosurgical techniques are as good as any other method of therapy. In carcinoma involving skin, cryosurgery has a special advantage in those situations when malignant tissue overlies bone. Cryosurgery is also useful in the management of dysplastic disease or carcinoma in situ, principally in the oral cavity and the uterine cervix. These applications are sufficiently valuable to be included in the textbooks concerned with those areas. Invasive cancer in other accessible sites, such as the oral cavity or the rectum, can be cured by cryosurgery, but the reports in the medical literature have not led to general use of the technique or descriptions of the technique in textbooks, except for occasional brief mention. Nevertheless, patients who are at high risk for surgical treatment because of coagulopathy or severe cardiopulmonary disease are appropriate candidates for the use of cryosurgical techniques. In the oral cavity, the possibility of preserving the bony structure is an attractive feature that maintains interest in cryosurgery. Unfortunately, there are no control studies to assist in the judgment of merit and in many cited reports, it is not easy to determine the survival rate or compare results with conventional therapy. In these sites, freezing techniques are more often used to achieve palliation of distressing symptoms by tumor bulk reduction, especially when little else can be done, and under these conditions, chemotherapy and radiotherapy are also commonly used. In less accessible sites, which generally require endoscopic or surgical exposure, cryosurgery is not often used. The treatment of carcinoma of the prostate gland by cryosurgery remains viable because of continued interest in the potentiation of immunologic defenses against carcinoma. This possible benefit is most evident in experimental tumors, but clinical evidence of benefit is not as clear.(ABSTRACT TRUNCATED AT 400 WORDS)