Medical treatments designed to help people can also be harmful or fatal. Around 2.5 million people die this way each year. So if any kind of medicine makes someone unwell, they or their doctor should report it. Those reports, from nearly every country in the world, go to the Uppsala Monitoring Centre (UMC) in Sweden.  As the Centre first director, Professor Ivor Ralph Edwards transformed it from a tiny operation with limited horizons into an internationally acclaimed scientific organization at the heart of the World Health Organization Programme for International Drug Monitoring. He was then succeeded by his wife, Dr Marie Lindquist. This is the story of how a new science developed and a passionate and dedicated pursuit of worldwide medicines safety, with an unerring focus on the welfare of patients. The pioneering work of Ralph, Marie and their collaborators on every continent protected the lives of millions of people. It may yet improve the lives of billions more.