Markham's works endlessly repeat themselves, and (like many other writers) he republished unsold copies of old books under new titles; sorting out all the bibliographical details of his works will provide steady employment for someone. The Company of Stationers' Register (23 April 1953) lists him as having revised for the press a poem, Thyrsis and Daphne, but the poem is not extant. Conceyted Letters, newly layde open (1618) has a preface signed "I. M.," but is now generally assigned to Nicholas Breton. Ariosto's Satyres (1608) is sometimes considered Markham's, though Robert Tofte claimed authorship in his Blazon of Jealousy (1615). Barnaby Rich's Allarme to England (1578), republished as Vox Militis (1625), is now assigned to G. Marcelline instead of Markham.

Markham's The Most Honorable Tragedie of Sir Richard Grinuile, Knight (1595) is dedicated to Charles Blount, the eighth Lord Mountjoy, and includes a sonnet addressed to Henry Wriothesley, third Earl of Southampton, that Frederick Gard Fleay...