The Canadian Medical Association's (CMA) Code of Ethics applies to all physicians, residents, and medical students in Canada. Learning about the code must be a part of every physician's education, and keeping current with it must be a part of every physician's continuing medical education. This article, based on a review of the 19 CMA codes of ethics issued from 1868 to 1996, shows how deeply the Code of Ethics is tied to the past, highlights those topics that have been part of every version, and demonstrates how the code changed over time. This article should assist medical educators as they develop teaching material on codes of medical ethics, and would be of interest to practising physicians.