The relationship construct between physicians and patients was explored in the context of medical education and evaluation focusing on the clinical performance of third-year medical students. The Relationship Instrument, a performance-based assessment, was constructed to measure interpersonal and communication skills of the physician interacting with patients. Data came from 370 third-year students in 4 medical schools. Standardized patients were selected and trained for case summaries, scripts, histories, and instruments used in each case to rate the clinical skills of the student physicians at establishing doctor-patient relationships. Preliminary analyses suggested that the Relationship Instrument was reliable and valid. Results with the instrument support a model of doctor-patient relationship that suggests that physician attributes such as gender, age, and race may have an impact on physician communication task and socio-emotional behaviors. There may also be a small but significant effect on patient task and socio-emotional behaviors due to physician attributes. The study also indicates that effective training of standardized patients is a critical component in performance assessments of this sort. Future research should focus on developing more indicators to assess doctor-patient relationship skills. Appendix A is the Relationship Instrument. (Contains 2 figures, 9 tables, and 22 references.) (SLD)