Georges Dreyer was the first Professor of Pathology at Oxford University and he held this post from 1907 to 1934. Although his main research interests were in bacteriology and immunity, he made important contributions to respiratory physiology, but these have been almost completely forgotten. He developed a new apparatus for administering low oxygen mixtures to test the effects of hypoxia in airmen during World War I, developed a high successful oxygen delivery system, was responsible for the first low-pressure chamber in a UK academic institution, and carried out some physiological measurements in the chamber that were years ahead of their time. His chamber was also used by a group from Cambridge and Turin, Italy for a series of important physiological studies. In spite of these contributions, almost nobody who works in respiratory physiology today, even in Oxford, recognizes the name of Dreyer.