Observation of a series of office visits by patients to family physicians provide information on physician-patient communication. During interaction on medical matters, the physicians instigated 80 percent of the interview. By way of contrast, when discussion of matters beyond the strictly medical situation occurred, 70 percent of the conversation was initiated by the patients. Irrespective of diagnoses, there were significant differences in the overall content of communications for patients from different socioeconomic groups, with more verbal exchange occurring with upper social class patients than with lower social class patients. Other patient factors which led to an increase in verbal interaction were chronic illness, emotional disorders, and ill-defined conditions. The analysis of categories of verbal interaction between physicians and patients proved to be a practical method of studying the physician-patient relationship, and provided guidelines for those seeking to make objective measurements of communication in family practice.