Suppurations of the middle ear are the most common diseases with which otologists come in contact. The most important of these are the chronic types associated with the formation of cholesteatoma. It is commonly thought that a relatively long period elapses between the initial suppuration and the formation of cholesteatoma. While studying in the laboratory of Prof. Dr. Nager at the University of Zurich, I observed a case that illustrates an early formation of cholesteatoma. It is known that cholesteatoma begins as an epidermization of the lining of the cavity of the middle ear. This process may take place by one of several different methods. Epidermization of the middle ear begins as an ingrowth of squamous epithelium from the external canal, following destruction of the epithelium of the middle ear and marginal perforation or total destruction of the drum. This destruction of the epithelium and drum of the middle ear