This year notes two major changes in the annual Detroit Cancer Symposium. The first is our intention of selecting top ics of broad interest to the cancer community and examining the subject from both a basic laboratory and clinical viewpoint. In this way, the importance of both elements of cancer research are noted and the interplay between them emphasized. Further, we believe that Symposia such as this act to stimulate the basic scientist and clinician to continue their studies with the know ledge of the impact that each has upon the other and the nec essary cooperation required to solve the cancer problem. The second change is the publication of this Symposium. The pre vious sixteen were not committed to manuscript form. Given the change in format and intent of the series, we believe that this and subsequent volumes will make important contributions to the cancer literature. The topic of Biology and Therapy of Acute Leukemia was chosen for the first Symposium because of its historical signif icance in cancer chemotherapy. The therapeutic rationale for human leukemia is the result of understanding the basic tumor biology largely derived from transplantable leukemias in exper imental animals. It is through these models, as discussed by Dr. Fred Valeriote, that we learned the cellular kinetics of leukemia, the antileukemic effects of new agents and the ef fect of growth perturbation by various chemotherapeutic agents and their combinations.