The role of the urban development of the city of S. Paulo (Brazil) is presented, in this study, in the light of the appearance of condition favorable to the establishment of the transmission of schistosomiasis in southeastern Brazil which is usually seen as a consequence of migration from the Northeast where the disease in endemic. Studies of the distribution of schistosomiasis in S. Paulo have given an exaggerated importance to migration. The spread of the disease in the municipality of S. Paulo (Brazil) is an example of a situation where the pattern of urban growth has been more relevant than migration. The occupation of the lowlands from the late 1950's onwards brought about the conditions for the establishment of disease foci. Up to then this was not possible for urbanization occurred exclusively in more elevated areas. Without a shift in the pattern of urbanization schistosomiasis wouldn't have occurred in the city of S. Paulo, despite intense migration.
Schistosomiasis; Urbanization; Transients and migrants