In Frontier Doctor, Reginald Horsman provides the first modern, scholarly biography of a colorful backwoods doctor whose pioneering research on human digestion gained him international renown as a physiologist. Before William Beaumont's work, there was still considerable controversy as to the nature of human digestion; his research established beyond a doubt that digestion is a chemical process. Beaumont received his medical training as an apprentice in a small town in Vermont and served as a surgeon's mate in the War of 1812. After the war, he practiced in Plattsburgh, New York, before making his career as an army surgeon. His chance for fame came in 1822, when he was serving at the lonely post of Fort Mackinac in Michigan Territory. A Canadian voyageur--Alexis St. Martin--was accidentally shot in the stomach at close range, and his wound healed in such a way as to leave a permanent opening. This enabled Beaumont to insert food directly into the stomach, to siphon gastric juice, and to experiment on the process of digestion both inside and outside the stomach. Because Beaumont had considerable difficulty in persuading St. Martin to stay with him so he could continue his research, his study was carried out sporadically over a number of years. In the early 1830s, with the support of Joseph Lovell, the surgeon general of the army, Beaumont and St. Martin went to the East Coast, where additional experiments were carried out. In 1833, Beaumont published Experiments and Observations on the Gastric Juice and the Physiology of Digestion, a book based upon his research on St. Martin and the work upon which his reputation primarily rests. His observations revealed more about digestion in the human stomach than had ever before been known, and his work was immediately praised in both the United States and Europe. After he left the army, Beaumont established a successful private practice in St. Louis, Missouri, where he spent the latter part of his life. Beaumont, a fascinating, argumentative character, was often engaged in public controversy. He was also good friends with several notable men, including the young Robert E. Lee. Frontier Doctor sheds welcome new light on the state of medicine both inside and outside the army in the early nineteenth century and provides absorbing information on the early experi-ments that set the research into human digestion irrevocably on the right course.