These papers contain seven letters to his wife (1808-1833), a fragment of autobiography on his painting and studies, a notebook containing copies of correspondence about his portrait of Washington, John Godman's Ode suggested by Rembrandt Peale's National Portrait of Washington (1824), and a commonplace book containing kitchen and medicinal recipes.

These papers reflect Isaac Hays' interests and activities in the medical profession and as an editor. His interest in paleontology, especially in the controversy with G. W. Featherstonhaugh, is also represented. There is one separate volume (77 letters) containing correspondence about natural history and naturalists, written to Hays by C. L. Bonaparte, George Ord, Thomas Say, and Charles A. Lesueur. The correspondence in the larger collection, however, contains much material on the American Journal of the Medical Sciences, particularly illuminated in the correspondence with John D. Godman. The I. Minis Hays material consists of letters from doctors, relating to medicine and medical publications and editing, as well as medical organizations. Most significant of the correspondence is that with John Shaw Billings (ca. 60 letters).