The methylene blue test for the control of the sanitary quality of raw milk has been in use for over twenty years. With the recent development of the resazurin test and its adoption by some foreign countries and by several health departments in the United States, controversies have arisen concerning the relative merits of the two tests. The possibility that the resazurin test is a more sensitive and quicker method of determining the quality of raw market milk has been of increasing interest to the Wichita-Sedgwick County Health Department and the Bacteriology Department of the University of Wichita. An attempt to correlate the results of several of the commonly used tests was initiated under the dual sponsorship of the University of Wichita and the Wichita-Sedgwick County Health Department, in order that the relative merits of the tests might be ascertained.