Hippocratic Oath
The Hippocratic Oath is an oath traditionally taken by physicians pertaining to the ethical practice of medicine. It is widely believed that the oath was written by Hippocrates, the father of medicine, in the 4th century BC, or by one of his students. It is thus usually included in the Hippocratic Corpus. Classical scholar Ludwig Edelstein proposed that the oath was written by Pythagoreans, a theory that has been questioned due to the lack of evidence for a school of Pythagorean medicine. Although mostly of historical and traditional value, the oath is considered a rite of passage for practitioners of medicine, although it is not obligatory and no longer taken up by all physicians.

# The Hippocratic Oath
Original, translated from Greek.
According to NOVA, the Oath is, as follows:
Hippocratic Oath -- Classical Version

# Modern relevance
Several parts of the oath have been removed or re-shaped over the years in various countries, schools, and societies as the social, religious, and political importance of medicine has changed.  Most schools administer some form of oath, but the great majority no longer use the ancient version, which praised Greek deities, advocated teaching of men, and forbade general practitioners from surgery, abortion, and euthanasia.  Also missing from the ancient Oath and from many modern versions are the complex ethical issues that face the modern physician.
Changed portions of the oath:
- To teach medicine to the sons of my teacher. In the past, medical schools would give preferential consideration to the children of physicians.
- To practice and prescribe to the best of my ability for the good of my patients, and to try to avoid harming them. This beneficial intention is the purpose of the physician. However, this item is still invoked in the modern discussions of euthanasia.
- Never to do deliberate harm to anyone for anyone else's interest. Physician organizations in most countries have strongly denounced physician participation in legal executions. However, in a small number of cases, most notably Oregon and the Netherlands, a doctor can perform euthanasia, by both his and the patient's consent.
- To avoid violating the morals of my community. Many licensing agencies will revoke a physician's license for offending the morals of the community ("moral turpitude").
- To avoid attempting to do things that other specialists can do better. The "stones" referred to are kidney stones or bladder stones, removal of which was judged too difficult for physicians, and therefore was left for surgeons (specialists). The value of specialization was recognized in that time. The range of knowledge and skills needed for the range of human problems has always made it impossible for any single physician to maintain expertise in all areas. This also highlights the different historical origins of the surgeon and the physician.
- To keep the good of the patient as the highest priority. There may be other conflicting 'good purposes,' such as community welfare, conserving economic resources, supporting the criminal justice system, or simply making money for the physician or his employer that provide recurring challenges to physicians.
- To avoid sexual relationships or other inappropriate entanglements with patients and families. The value of avoiding conflicts of interest isn't often questioned.

# Modern versions and alternatives
A widely used modern version of the traditional oath was penned by Dr. Louis Lasagna, former Dean of Tufts Medical School. 
In the 1970s, cultural and social forces induced many American medical schools to abandon the Hippocratic Oath as part of graduation ceremonies, usually substituting a version modified to something considered more politically up to date, or an alternate pledge like the Oath or Prayer of Maimonides.
The Hippocratic Oath has been updated by the Declaration of Geneva. In the United Kingdom, the General Medical Council provides clear modern guidance in the form of its 'Duties of a Doctor' and 'Good Medical Practice' statements.