This paper discusses two conceptual models intended to facilitate research on the effects and effectiveness of telemedicine. The first is a conceptual framework to study the efficacy of telemedicine as a diagnostic medium. Using conditions that are carefully chosen to serve as indicators of effectiveness, we recommended the analysis of sensitivity and specificity to establish the accuracy of telemedicine in relation to conventional health care delivery. Suggested guidelines for interpretation of the results are discussed. The second model is a scheme for classification of telemedicine applications that is based on processes of care rather than on specialties or disorders. The purpose of this classification scheme is to facilitate research on such variables as costs, access, acceptability, and effects on practice patterns.