Introduction - Few studies have been published on sexual minorities—lesbians, bisexuals, and transgender individuals—who remain poorly understood, even though knowledge about the male homosexual population has improved since the onset of the AIDS era. Transgender and AIDS advocacy organizations, along with the Regional Center for AIDS Information and Prevention (Crips), conducted an initial exploratory study among transgender individuals to describe their social situation, sexual behaviors, and use of healthcare services. Materials and Methods - A questionnaire was developed by Crips and Act Up-Paris and distributed online from May to June 2007. Results - A total of 179 people responded to the questionnaire online. The data collected reveal socioeconomic characteristics similar to those of the general population, but with lifestyles marked by fewer romantic relationships, less sexual activity, more sexual encounters involving the exchange of money, greater risk-taking, and higher rates of psychoactive substance use. Compared to gay men, similarities are observed in sexual behavior (few long-term relationships) and preventive practices (risk-taking during oral sex), as well as differences (less sexual activity). Experiences of discrimination are common. Discussion-Conclusion - It is likely that this initial exploratory study failed to include highly vulnerable groups such as immigrants and sex workers whom organizations encounter in the field. It is necessary to continue and expand knowledge about the transgender population in order to develop appropriate prevention and care services and to support the movement toward recognition of their specific needs. (R.A.)