Alkoxyglycerol derived from shark liver oil is marketed in Denmark and mentioned in popular articles as a supplementary agent in the treatment of cancer. A questionnaire investigation carried out in the Department of Oncology and Haematology in Odense Hospital revealed that approximately 1/3 of the patients in active neoplastic therapy employed shark liver oil preparations. The clinical investigations of alkoxyglycerol were all carried out on patients with cancer of the uterine cervix. All of the investigations were carried out by the same Swedish research group. Only a minority of the experimental material was blinded. No documentation was found for inhibited tumour growth or reduced mortality resulting from treatment with alkoxyglycerol. The number of cases of irradiation damage were found to be fewer in the groups treated with alkoxyglycerol, but the difference may be partially explained by different subdivision into stages. Alkoxyglycerol results in increase in the leukocyte and thrombocyte counts while higher or lower doses have, apparently, the opposite effect. The available literature concerning the clinical effect of alkoxyglycerol is limited and unsystematic and does not support the employment of alkocyglycerol in the treatment of cancer.