On not harming: two traditions.

While ancient in origin, the principle, "Do No Harm," continues to occupy a prominent place in many present-day medical ethics codes. Of all the versions of the principle two distinct varieties can be distinguished. These parallel two ethical traditions. This paper develops the contrast between the two versions, relates them to the two ongoing ethical traditions, and then uses insights from contemporary ethical theory to demonstrate the significance of one of the versions. Finally it suggests some contemporary applications for a medical ethic and medical education.