Abstract: Sir William Osler bequeathed his library to McGill University in 1919, and the 8000 volumes arrived in Montreal a decade later. Then, as now, the collection consisted of both primary works (rare books) and secondary commentaries, and current works on the history of the health sciences. In the last 80 years, the collection has grown considerably, and the library now adds about 1000 books each year, mainly current publications, and receives 200 current serial titles. The Osler Library, which is one of the largest "history of medicine" libraries in the world and the largest in Canada, tries to collect current material on the history of the health sciences from all over the world and attempts to collect all medical history published in Canada. The Osler offers its resources to researchers through its Web site, publications, and Research Travel Grant program.