John Gregory (1724-73) wrote the first modern, professional medical ethics in the English language, appearing as Lectures on the Duties and Qualifications of a Physician in 1772. This paper examines Gregory's medical ethics as a blend of modern methods of medical science and ethics with premodern ideas. The paper begins by situating Gregory's medical ethics in the context of both private medical practice and the care of patients at the Royal Infirmary of Edinburgh, focusing on the crisis of intellectual and moral trust that prompted Gregory to lecture and write on medical ethics. Drawing on the modern methods of Francis Bacon's philosophy of medicine, and David Hume's science of morals, Gregory bases his medical ethics on the complementary capacities of openness to conviction and sympathy. His moral exemplars of the virtues of candour, steadiness, and tenderness were women of learning and virtue, reflecting the premodern idea of chivalry in the life of service to the sick.