Describes a planned, computer-implemented decision-aiding system to help in patient management during leukemia chemotherapy. Key variables in leukemia chemotherapy are compact and essentially quantitative; the system will provide an explicitly quantitative method for aiding those components of physician decisionmaking that are quantified and structured, while leaving to physician judgment, intuition, and clinical experience the more contextual elements. The paper describes plans for a series of five nested computer programs interacting with a physician through interactive graphics. These programs, which will be based on mathematical models of biological processes that incorporate aspects of the biology and pharmacology of leukemia and its therapy, should help to guide the querying and use of the clinical database. Each module will concentrate on a different aspect of the treatment problem. The modular construction will permit clinical use of the individual components as they are developed, and prior to their ultimate integration into a complete system. 16 pp.