The classic immunodeficient mutants nude, scid and rnu have an important function in experimental cancer research: they allow unique methods of investigation and provide data of clinical relevance. This volume presents the state of the art of research work based on the use of these immunodeficient animal models. One section is dedicated to the biological aspects and immunological properties of immunodeficient mutants. Another part includes articles on xenogenous transplantation of human tumors, focusing on the establishment of transplantable lines, growth characteristics and tumor markers. Special attention is given to new approaches in the fields of chemotherapy, radiation therapy and immunotherapy. Various contributors consider in vitro methods as alternative models. In addition to current data, this publication contains useful technical and methodological information and is therefore valuable not only for specialists but also for scientists entering the field of experimental cancer research.