The traditional standard of objectivity in medical diagnosis is to require avoidance of interference by psychic phenomena. The doctor should become depersonalized, so as not to prejudice the collection of information with psychic elements. Modern knowledge of the participation of the psyche in the genesis of organic diseases compels us to consider this principle. The medical interview is now expanded to the affective level. It should include the study of the doctor-patient relationship, with due consideration of both the patient's and the doctor's role. Thus, by the inclusion of the examiner himself in the diagnosis there is introduced a new element in clinical observation. The constructive utilization of psychologic elements contained in the doctor-patient relationship encounters an obstacle in the countertransference difficulties of the doctor, which have to do with certain defenses, institutionalized in rules that continue as the basis of clinical conduct. The doctor tries to escape, without realizing it, from emotional participation with the patient. His paranoid anxieties lead to a pseudo-objectivity in which the emotional realities are obscured and devaluated. To this recourse is added the omnipotent control mechanism. Depressive identification with the destroyed object is the basis of exaggerated attitudes of compassion and pity. Unconscious fantasies mobilize feelings of guilt that may disturb the clinical work. A correct behavior demands that the doctor be able to take into account his own countertransference reactions. The diffussion of psychoanalytic instruction, which includes psychic preparation of the student (didactic analysis), will inevitably invade all medical science. We must revise the knowledge and the personal attitudes of the physician, beginning with the basic remodeling of the principles of professional teaching, a change it is no longer possible to avoid.