In an evaluation of the efficacy of four two-way telecommunication systems for use in primary care, more than 1,000 patients seeking care at a community health center received an additional remote examination by use of either color television, black and white television, still-frame black and white television, or hands-free telephone. The diagnosis, clinical tests and X rays requested, and proposed patient management were compared to the actual care received by the patients at the health center. There were no significant differences between any of the modes in relation to diagnostic accuracy, time for the diagnostic interview, tests requested, or referral rates. Furthermore, patient attitudes did not vary significantly. Thus the relatively inexpensive telephone proved to be as efficient and effective a means for delivery of remote physician care as did any of the visual communication systems.