Prostitution involves the exchange of sexual services for economic compensation. As sexual behaviour is an important determinant in transmitting HIV and sexually transmitted diseases (STDs), sex workers (SWs), transgenders and clients are often labeled as a "high risk group" in the context of HIV and STDs. It has been documented that female sex workers in particular have an increased prevalence of untreated STDs and have been hypothesized to affect the health and HIV incidence of the general population. People involved in prostitution are a cause for concern from both public health and economic perspectives. However, little is known about why they remain in this type of activity given the risks prostitution presents, and even less is known about how to intervene and interrupt the complex cycle of prostitution. The aim of this paper is to provide a clinical and epidemiological analysis of the relationship between prostitution, sexual behavior and outbreaks of STDs; to assess the role that migrants, transgenders and clients of SWs have in prostitution and in the outbreaks of STDs. In addition, we also want to highlight how new sexual networks, like the Internet, have become an increasingly important vehicle to sharing information about prostitution, sexual behavior and STDs. Finally we present what may be the prevention strategies and the goals in order to stem the spread of STDs among these hard-to-access groups.