This paper will examine the manuscript evidence for Philo’s treatise De mutatione nominum. Wendland (in the Cohn-Wendland edition) utilized only two mss., A (Monacensis gr. 459) and B (Marcianus gr. 41). The narrow manuscript base provides many opportunities for conjectures, both those of Wendland and those of other scholars. Some of these are printed by Wendland, and many more are included in the apparatus for consideration. However, the treatise is preserved in other mss., some of which have not been investigated systematically. Three of these are: Cantabrigiensis Collegii S. Trinitatis B 9 6, Oxoniensis Collegii Novi 143, and Coislinianus 43. All were used by Mangey, and are occasionally cited by Wendland via Mangey. At a few places their readings find their way into Wendland’s text. This paper will survey the textual issues of this treatise, will report on a fresh examination of the three mss. mentioned above, and examine in detail some of the textual problems within this work.