In a former report on the distribution of actinomycosis in the United States, we stated that our complete protocols of case reports obtained from various sources would be published as a geographic index of the disease in this country. The data are arranged geographically, the forty-eight states being grouped according to the usual method. The case reports for each state are subdivided into those that have been published previously and those that have not been published previously, but which have been reported to us, either as a response to individual letters of inquiry to health officers or the larger hospitals, or in reply to requests for such data published in various medical journals. Another group of case reports is made up from the records of the Mayo Clinic. The total number of cases studied is 670. All cases reported in the literature that were included in Ruhräh's review are marked