In Japan, only a few public libraries provide e-mail reference services. To help public libraries start e-mail reference services, the authors investigated reference questions received by libraries via e-mail and traditional face-to-face services. The authors found that research questions are more frequently observed among e-mail questions and questions about the local area are slightly more frequently observed. Librarians who are planning to start e-mail reference services should be aware of these tendencies. (Contains 10 tables.)