The diagnostic evaluation, representing a fundamental activity in psychiatric practice and research, requires a particular ethical responsibility on the part of the clinician. The author proposes the following aspects as being important for a comprehensive and ethically sensitive diagnosis: (a) incorporation of the patient's subjective perspectives and understanding of his/her disease, (b) consideration of the patient's quality of life, (c) assessment of the positive aspects of health, (d) awareness of group-dynamic and psychodynamic factors in the diagnostic situation, (e) the clinician's professional competence, value orientation and personal identity, (f) therapeutic optimism as a basic attitude. The patient's active involvement is emphasized since he is the real expert as far as his individual, social, religious and ethical needs and values are concerned.