To remain at the forefront of scientific discovery, investigators continually are challenged to apply new approaches, instruments, and models to their work. Research institutions work to foster the exchange of ideas and resources, but this objective becomes more difficult to meet as the organization's size and complexity increase. To facilitate communication among researchers that use mice in their work and to provide increased opportunities for resource sharing, an electronic discussion group was formed at The Johns Hopkins University. The discussion group (jhu-mousers) is restricted to individuals within the institution's three campuses, and its 145 subscribers comprise faculty (including veterinarians), postdoctoral fellows, graduate students, and technicians. During its beginning 2 1/2-year period, jhu-mousers has received 207 postings that include seminar announcements; resource information; requests for mice, equipment, biological reagents, and technical assistance; and responses to these requests. The value of the electronic mailing list is evidenced by the fact that 70% of requests for resources or technical help have received at least one response, and this figure is likely to be underestimated because off-line responses are not included. Because the mailing list provides opportunities for tissue sharing and is conducive to refining experimental procedures used in mice, its application promotes the use of alternatives in animal research. To promote and assist the development of animal-user discussion groups at other institutions, the administration, applications, and benefits of an electronic mailing list for mouse users are discussed here.