London, Wellcome Library, MS 411 is a codex in one volume which dates from the late fifteenth century. It houses a collection of practical treatises and tracts in English and Latin, in verse as well as in prose, on different topics including prognostications, nativities, medical astrology, reproduction, toxicology, bloodletting, etc. In this paper, the Middle English anonymous treatise on venomous bites, written in prose and held in folios 56r to 61r, is taken into consideration. The objective is twofold: on the one hand, to examine the contents, transmission and sources of the text and, on the other, to describe it from a physical standpoint. Investigation on those aspects of the treatise contained in Wellcome MS 411 can shed some light on the function and diffusion of the text, and may also prove significant for a better understanding of it.