The historical changes made by the modernization in Latin America were extremely connected with the changes occurred in the practice of prostitution. This paper will examine the relationship between, the modernization and the "white slavery" speech, with the health policy and the prevailing sexual morality from the officiality, with the propose to make a reflection about how these structural and discursive changes made effect on the practice of prostitution and its regulation. The period chosen for this study begins from the early regulation in 1874 in Argentina, until its prohibition in 1936. Chile, Argentina and Uruguay have been selected as the space of comparative analysis, because, apart from the fact that they share the same geographic area of the Latin America south cone, they also share characteristics that show, on a bigger level, the historical changes and its mark on the prostitution: Government modernization, secularization of its institutions, urbanization because of the internal and external migrations, and the regulation of the prostitution under the French Napoleonic model.