The Sir William Osler Collection, distinct from the Bibliotheca, is an extensive archival holding of Osler's correspondence (including eighteen hundred original letters), daybooks, accounts, engagement books, legal documents, book invoices, membership certificates, notebooks, lectures, addresses, newspaper clippings, photographs, books with manuscript additions, and miscellaneous loose items formerly inserted into individual books in his library. The collection also contains various family papers, including correspondence of Lady Grace Revere Osler and Edward Revere Osler.

Collection consists of a manuscript book containing numerous short handwritten excerpts, fragments of poems, reflections, and quotations from various authors, primarily focused on flowers, health, and wisdom. It also includes pages of handwritten poems by C.J.C. Briscoe, the uncle of J. Kerr. Includes a six-page typewritten fable titled "The butterfly and the ant: a fable," written in 1886. Includes a one-page typewritten article titled, "Observations of the Works of Modern Flower Painters, Miss Lawrence." This article is "a copy made from a book entitled "A Practical Essay on the Art of Flower Painting" by John Cart Burgess, Professor and Teacher of Drawing and Painting, and an Exhibitor at the Royal Academy of Arts, London, 1811" (from a note on the bottom of the page).

Consists of a notebook Robson kept as a student at the Banting Research Institute at the University of Toronto from June to September, 1930. The notebook comprises over 60 manuscript pages, plus 31 manuscript pages attached to the end, 1 loose leaf of manuscript medical notes, approximately 50 ink drawings of various sizes of experiments, 26 black and white photographs pasted in, including a photograph of Sir Frederick Grant Banting in his office, the Banting Research Institute and its faculty, and experiment apparatuses. Also includes 13 mimeographed pages (pasted in) containing 12 different experiments, the printed programme for the formal opening of the Banting Institute on 16 September 1930, and 9 newspaper clippings pasted in related to the opening of the Institute.