Frank McClean (1837-1904) was not only an astronomer and pioneer of objective prism spectrography, but also an accomplished and systematic collector of art, books and manuscripts. McClean's collections, which were left to the Fitzwilliam Museum, Cambridge, on his death, were at that time the most notable bequest since the Museum's foundation. The fifteenth- and sixteenth-century printed books in his bequest, most of them produced in continental Europe, are described here in detail, with bibliographical descriptions and information on their provenance. Illustrated books are listed separately. The author of the catalogue, Charles Edward Sayle (1864-1924) was an erudite and popular librarian whose career was devoted to cataloguing and editing rare books in the University of Cambridge. His obituary praised him as 'a fine example of the type of man who likes to catalogue things in the right order'.