We are asking for continued support of a training grant which has been successful in attracting young physician-scientists into academic medicine. The grant provides an opportunity for post-graduate clinicians from the general clinical area of hematology (internal medicine, pathology, pediatrics, transfusion medicine) to gain training and experience in the study of blood cells at the fundamental level. Top priority is given to individuals early in their post-graduate clinical training so as to optimalize the chance of a long-term academic commitment. Most trainees accepted will be physicians who have completed from 1-3 years of clinical training with limited research backgrounds although some trainees will be PhD degree holders. Two to three years of fundamental training in the molecular and cell biology of blood cells will be provided to successful applicants. A formal plan for each trainee including coursework necessary for an optimum training experience will be planned by the immediate research supervisor, the program directors and the Advisory Committee. In addition, each trainee will participate in a variety of formal conferences in Hematology and related disciplines as well as numerous seminars by international experts in the areas of molecular and cell biology of blood diseases. The solid foundation for an intensive research training experience is provided by distinguished faculty with well supported individual research programs and extensive interdepartmental cooperation in research and training. A strong aspect of this program and one which as been strengthened is the dual clinical department-basic department structure. This begins with the Co-Principal Investigators from Medicine and Biochemistry and extends as a balance of trainee supervisors in both clinical and basic departments. The optimal training environment provided by the diverse experience faculty, extensive modern facilities, rich source of patients for biologic material, extensive collegiate core facilities and a long history of success in training future academic physicians in hematology should insure a continued high rate of success in preparing well-qualified academic hematologists with research skills at the interface between molecular biology and clinical medicine.