In brief, cancer immunology studies the reaction of the host to the development and growth of the invading malignancy.1 It is hoped, not naively, we believe, that more knowledge of this immunologic background may help to contribute to the control and perhaps even to knowledge of the cause of cancer. Many who work in cancer immunology believe it is necessary now to do more investigative studies of cancer immunology in man, not in animals. The dermatologist should be interested in cancer immunology because of the easy availability of the skin for the direct observation of tumors and for the use of immunologic procedures. Immunology has been an important discipline in the training of dermatologists. From the very nature of the specialty, dermatologists have not believed in the formal lines between the several disciplines of medicine; as Horsfall2 now indicates for other disciplines of basic sciences, "It is no