Abstract: The work performed by the clinical chemist may deeply affect the decisions of the doctor and the well-being of the patient. Yet in contrast to the doctor and to the nurse the clinical chemist usually has no personal relationship with the patient. Being encumbered by much technology and anonymity is itself a reason for scrutinising his involvement in issues of health care ethics. This is an attempt at clarifying some major aspects: the relationship of his professional ethics to medical ethics as a whole, his ethical obligations to the patient and to society, and other aspects.The author, a clinical chemist, asserts that members of his profession may have to bear some of the responsibility for resolving ethical dilemmas in treatment decisions, although they rarely have direct contact with patients. He describes three situations where data passed from a chemist to a clinician has ethical implications for patient care. He warns that the anonymity of the clinical chemist and the impact of laboratory work on treatment decisions could contribute to a dehumanizing trend in health care. BenGershôm concludes his article with some proposed ethical rules that he has submitted to the International Federation of Clinical Chemistry.