The use of electronic mail (e-mail) is increasing among both physicians and patients, although there is limited information in the literature about how patients might use e-mail to communicate with their physician. In our university-based internal medicine clinic, we have studied attitudes toward and access to e-mail among patients. A survey of 444 patients in our clinic showed that 46% of patients in the clinic use e-mail, and 89% of those with e-mail use it at work. Fifty-one percent would use e-mail all or most of the time to communicate with the clinic if it were available, and many of the communications that currently take place by phone could be replaced by e-mail. Barriers to e-mail use include privacy concerns among patients who use e-mail in the workplace, choosing the appropriate tasks for e-mail, and methods for efficiently triaging electronic messages in the clinic.