The term "pyoderma" denotes a purulent infection of the skin due to pyogenic organisms, ordinarily staphylococci. During the last two or three years, we have observed a number of rare instances of extensive sloughing ulceration of the skin, similar in many respects to fulminating echthyma gangrenosum, but essentially a form of pyoderma, in which the hemolytic streptococcus and the staphylococcus were found repeatedly. Besides the cutaneous lesions, each patient presented a serious infectious process of long standing elsewhere in the body, which served to prepare the way for the ulcerations of the skin by producing marked constitutional debility. During the period of observation in each case throughout a series of exacerbations and remissions, it appeared evident that there was a definite parallel relationship between the underlying debilitating disease and the cutaneous manifestations. Of the five patients whose cases form the basis of this report, four had chronic ulcerative colitis, with