Over 60% of National Institutes of Health (NIH) extramural funding involves animal-related research. Mice represent approximately 80-90% of the animals used in biomedical research, yet mice are often the least understood laboratory animal species. The number of genetically engineered mouse (GEM) mutants has risen substantially and the use of GEM models for hypothesis-driven research has also increased. However, the scientific community lacks sufficient numbers of adequately trained experts to accurately characterize these animals and validate the models. This letter is intended to increase your awareness of the pending disaster and to solicit your support in finding solutions. Laboratory mouse populations are straining the housing capacity of research institutions. This growth remains unabated. On the heels of several large-scale mouse mutagenesis programs and considerable growth in GEMs created by individual laboratories, the NIH is embarking upon the ‘‘knock out mouse project (KOMP),’’ with the goal of knocking out every functional gene in the mouse genome. Similar large-scale efforts are launching in Canada (NorCOMM: North American Conditional Mouse Mutagenesis Project), Europe (EUCOMM: European Conditional Mouse Mutagenesis Programme), and Asia. Recently, an International Mouse Knockout Consortium has been formed heralding a cooperative multinational program (Nature 446, 469–470 (29 March 2007)). These trends have created rich opportunities and critical demand for expert comparative pathologists who are knowledgeable in mouse biology and human disease. The genomics era has demonstrated the conservation of genetic information across species that gives credence to Osler’s suggestion of there being only one medicine. While the body systems do similar things across the spectrum of mammals each animal has its own characteristics in responding to various diseases. In this context the mouse as a model of human disease has to be interpreted by pathologists who have knowledge of specific disease states in both humans and mice and can evaluate mouse tissues knowing their unique similarities and differences to humans. Thus, a unique specialty in pathology is required for the immense use of mouse models to be accurately evaluated in terms of comparative medicine. The scientific literature is replete with erroneous interpretation of phenotype by scientists (including pathologists) lacking expertise in mouse pathology. As much as it would be unacceptable to analyze structure of a molecule using x-ray diffraction data without a formally trained expert, it should be unacceptable to publish papers and fund grants purporting to model human disease without the expert review of a formally trained, knowledgeable pathologist. However, pathologists are frequently missing from important applications and papers. Effective mouse pathology requires a global understanding of mouse biology, euphemistically termed ‘‘Muromics’’ (for a more thorough discussion of Muromics, see Barthold, Comp Med. 2002 52:206–23). In addition to comparative medical pathologists, there is a critical shortage of veterinary pathologists with expertise in the mouse. The lack of pathologists to serve biomedical research, and mouserelated research in particular, has been emphasized in several recent National Academy reports. NIH recognizes this problem, but is attempting to address this shortage with only scant investment of resources. Furthermore, NIH funding mechanisms allow for scientific training and research, but not discipline training, such as pathology. Financial austerity of the NIH budget does not bode well for solving the problem. Partnership and investment by industry, which waits at the doors of academic institutions to hire what few pathologists are being trained, is critically needed. Why comparative pathologists? They are the gatekeepers of translational research. If mouse models are to be valid models of human disease, they must be accurate models. Comparative mouse pathology requires a unique set of skills and knowledge base that is not possessed by most investigators, or for that matter, the standard pathologist. It requires familiarity with the nuances of the mouse, and knowledge of the human condition that the mouse model purports to emulate. NIH is investing significantly into mouse-related research, but it is all for naught without validation, effective application, and translation toward the advancement of human health. The pathologists provide validation. A 2004 Workshop sponsored by the National Center for Research Resources (NCRR) came to the conclusion that the United States has less than a dozen individuals that can be identified as legitimate ‘‘mouse pathologists’’ or more correctly, Veterinary or Physician Pathologists trained in or experienced in the pathology of mice. Further, most of these dozen or so individuals are approaching retirement age. Where are the mouse pathologists of the future and who is going to train them? The mouse genetics community, encouraged by national and international organizations, is creating a glut of mice but not the human resources necessary for their characterization. One solution to our dilemma is to develop an ‘‘electronic consortium’’ of existing ‘‘experts’’ in various aspects of J Vet Diagn Invest 19:455–456 (2007)