Medical practitioners of the sixteenth century had their own body of special terms, just like the doctors of this century. The author examines medical terminology used in a selection of thirteen medical works published between 1547 and 1612, and compares it with the treatment of these words in the OED and other dictionaries of today. This study reveals errors, omissions, and biases which raise questions for lexicographical tools in general. This is an authoritative account of a specialized vocabulary which will be of considerable influence on future studies of sixteenth-century English.