Our purpose in this study is to determine whether the prophylactic administration of sulfathiazole prevents the development of gonorrhea. The existence of an inordinately high gonorrhea rate among certain troops makes the development of an easily administered chemical prophylaxis particularly important. The following incomplete experimental data are published as a preliminary report because of the encouraging results already achieved. Joses1 and Kline and Ryan2 have published articles on the subject of sulfathiazole prophylaxis. In both studies sulfathiazole was given in divided doses after exposure. In the former study gonorrhea did not develop in any of 350 men who received sulfathiazole; in the latter, of 1,000 who received the drug 3 developed gonorrhea. METHOD OF STUDY The test group consisted of a company of approximately 1,400 Negroes. The control group consisted of approximately 4,000 Negro troops from the same post. The method of administering sulfathiazole was as follows: All