Purpose and conclusions Dr. Alice Stewart, 1906–2002, came from a medical background which included a strong commitment to social justice and equality. Her father became Professor of Medicine at Sheffield University and her mother was one of the first women to qualify as a doctor, and together they practiced in Hillsborough, near Sheffield. Having qualified as a doctor herself in 1932, Alice worked in London hospitals before moving to Oxford, where she became a pioneer in epidemiology. Early in her career, she showed that X-raying pregnant women was a cause of childhood leukemia. Her later work focused on the harmful effects of low-level radiation on nuclear industry workers, the role of background radiation and she went on to question the dose limits set for radiation protection. All her results were initially challenged, but subsequent studies have borne out her findings. Conclusions Dr Alice Stewart’s research was pioneering, fundamental and challenging, and is now widely accepted.