The main goal of this study, in the field of the Anthropology of Policy, was to analyze the social construction of the AIDS vulnerability of truck drivers in the South of Brazil, examining the national HIV/AIDS prevention policies. The discourse of three social actors were analyzed using the Medical Anthropology framework: (i) the national gonvernmental AIDS agency, (ii) the Non Governmental Organizations supported by the National AIDS Program to execute prevention projects targeting truck drivers, and (iii) the truck drivers themselves, passing through Rio Grande do Sul state. Three important themes traverse this study: (i) globalization (and the global/local relations), (ii) the identity of a social group or a community, and (iii) the construction of a sexual culture. To understand the social construction of the truck drivers’ vulnerability, I followed the route that this idea went through different institutions and levels. Beginning at international intergovernmental agencies such as the World Health Organization, the United Nations AIDS Program (UNAIDS) and the World Bank, the course followed through the analysis of scientific research on the theme, and finally the national AIDS agency’s discourse. The route finally came to how NGOs seize and use the idea that truck drivers are a vulnerable group, ending with how the truckers themselves perceive their vulnerability to HIV, AIDS and sexually transmitted infections. The study was limited in scope by the action of NGOs who had developed publicly funded projects targeting truck drivers. Methodologically, the study collected and analyzed data of different origins, types and qualities. Official documents, grey literature, scientific papers on truckers and HIV/AIDS, as well as NGO project proposals were studied. Data collection also involved an ethnography and a survey (N=854) of truck drivers. Both qualitative and quantitative studies of truckers were developed in Rio Grande do Sul, southernmost state of Brazil, in the cities of Porto Alegre, Gravataí, Canoas, Rio Grande and Chuí. Truckers are immersed in a social network, both in the truck stops (fuel stations and customs) and in their places of origin (where family relations prevail). The social universe of the truckstops is not a simply a transitory place: there are rules of conduct, leaderships, social spaces which are symbolic and geographically marked, and a number of persons who maintain diverse relations amongst themselves for a long time. Truck drivers did mention inconsistent use of condoms, specially with regular or fixed partners, that certainly increases their vulnerability to HIV and sexually transmitted infections. However, inconsistent condom use, and the availability of commercial sex workers, is not exclusive to truckers or truck stops. Emphasis is given to the programmatic or institutional vulnerability of truck drivers.