The oath attributed to Hippocrates, the master physician who lived in the 5th Century B.C., has been repeatedly revised and updated to reflect the language and cultural beliefs of the period. Hundreds of oaths exist today.

Slightly different versions were recited at commencement - the transition from student to doctor - at each of the five medical schools in and around Philadelphia in May 2009. The same or other versions were recited four years earlier, during  the "white coat" ceremony that signifies the beginning of a doctor's training.