Blastomycosis was first recognized in the United States by Rixford and Gilchrist1 in 1896. Since then, most valuable studies have come from Chicago, where the disease seems to be very prevalent or at least readily recognized. An extensive review of the literature is impossible in a paper of this scope, but the monographs of Ricketts2 and of Stoddard and Cutler3 and the numerous papers originating in Chicago may be consulted. During the last five years I have had the opportunity of studying six cases of systemic blastomycosis and thirteen of the local skin variety. The diagnosis in each case was based on the clinical and bacteriologic observations. It was confirmed by the study of biopsies and the finding of the typical organism and cellular reaction in the tissue. All of the systemic cases ended fatally, while the local cases were cured under the administration of potassium iodide