This resource guide reflects an analysis of the world literature, for the period between 1983 and June, 1995. It provides an overview of the current status of biological models that can facilitate advances in the development of drugs and radiopharmaceuticals and allows rational choices of the appropriate models for investigations specific to understanding disease processes and the development of treatments for diseases afflicting society and its members. Guidelines for the use of animals in research are necessarily re-stated in this monograph, as well as brief remarks concerning alternatives. A brief review of philosophical, ethical and moral arguments concerning the use of animals in research and testing is provided as background on the past and current situation in the use of animals. This resource is intended for radiopharmaceutical scientists, pharmacists, physicians, veterinarians, post- graduate researchers, members of animal care and ethics committees and other professionals involved in biomedical research, drug and radiopharmaceutical development.