The computer is transforming patient-physician communication. Physicians are already using electronic mail (e-mail) in physician-to-physician consultation, medical journal dissemination, and hospital-physician communication. This article addresses the value of e-mail for patient-physician communication. It explores the nature of this electronic medium, outlines published guidelines, delineates expected benefits and potential complications, and proposes how to incorporate e-mail into health information systems. This article is designed to help guide clinicians and health care delivery organizations in the use of e-mail with patients to enhance rather than complicate the provider-patient relationship. Unique advantages of e-mail in the clinical setting include: the ability to offer routine transactions and patient education; increased efficiency; the self-documenting nature of this medium; cost-effectiveness; and serving as a clinical extender.