The collection consists of eight series. The attempt has been made to maintain the original order as much as possible, and particularly in the correspondence and scientific data series. Much of the material, however, was transmitted and accessioned in small portions in the years 1963-1966, and in some cases items were placed on display in the Library before being arranged in series. The microfilming, moreover, was carried out before the final arrangement and analysis of the collection could be made; somewhat premature filming decisions have, therefore, affected the final arrangement that is presented here and some items are missing or poorly described on the film.

The Leo Loeb papers consist of Dr. Loeb’s note books, lectures, research notes and manuscripts,  and scrapbooks. The series of personal correspondence is largely incoming and fragmentary with some letters filed in  Series 8: Bibliographical notes on the medical literature, manuscripts, research pathology data and occasional related correspondence, Undated & 1921-1958. The papers also include notes and drafts for two unpublished books. One is on mental processes and titled _Psychical Goods_or _The Imponderables. _The other unfinished book is on cancer.

This collection contains lectures, memoranda, data, correspondence, notes, clippings, and reprints.