Biomedical research on captive chimpanzees incurs substantial nonhuman animal welfare, ethical, and financial costs that advocates claim result in substantial advancements in biomedical knowledge. However, demonstrating minimal contribution toward the advancement of biomedical knowledge generally, subsequent papers did not cite 49.5% (47/95), of 95 experiments randomly selected from a population of 749 published worldwide between 1995 and 2004. Only 14.7% (14/95) were cited by 27 papers that abstracts indicated described well-developed methods for combating human diseases. However, detailed examination of these medical papers revealed that in vitrostudies, human clinical and epidemiological studies, molecular assays and methods, and genomic studies contributed most to their development. No chimpanzee study made an essential contribution, or, in most cases, a significant contribution of any kind, to the development of the medical method described. The approval of these experiments indicates a failure of the ethics committee system. The demonstrable lack of benefit of most chimpanzee experimentation and its profound animal welfare and bioethical costs indicate that a ban is warranted in those remaining countries - notably the United States - that continue to conduct it.