Policies regarding post-sexual exposure prophylaxis (PEP) and the "treatment as prevention" strategy have strengthened preventive measures against HIV transmission. This study aimed to describe the perceptions of people with HIV/AIDS regarding prevention of sexual transmission of HIV in the context of serodiscordance. Two focus groups were conducted, with 13 HIV-positive participants who were in serodiscordant relationships: one group with people in stable partnerships and the other in non-stable relationships. Just over a third of participants were aware of PEP and "treatment as prevention". There was a consensus that it is easier to use safe-sex practices in non-stable serodiscordant relationships, it is easier to use safe-sex practices. Some advantages of the new policies were mentioned, despite the concern that condom use might be neglected. The importance of healthcare teams' actions among serodiscordant couples regarding prevention of sexual transmission of HIV was highlighted. A great number of advances can be perceived since Acquired Immunodeficiency Syndrome (AIDS) was first identified in the early 1980s. Nevertheless, AIDS still remains at epidemic rates, representing a public health problem in Brazil. 1 With the advent of antirretroviral therapy (ART) -which acts on the multiplication of HIV causing a reduction in the viral load and, consequently, an increase in CD4 T-cells and recovering of the immune system -AIDS is currently considered a chronic disease that, even with no cure, enables that people living with HIV/AIDS (PLWHA) have a satisfactory quality of life. [2][3][4][5] By promoting the distribution of antirretroviral therapy from 1996, the Brazilian Public Health System enabled access to treatment as a possibility of PLWHA achieving a good quality of life. As a consequence, other issues have taken place, such as the constitution of serodiscordant couples -a term used to refer to heterossexual or homossexual couples where only one of the partners is HIV-positive. 6,7 Preventive measures against sexually transmitted HIV undergone significant changes over the course of the HIV epidemic. The regular and consistent use of male condoms, followed by the female condoms, was the first preventive measure for fighting against HIV, with good efficacy levels at relatively low costs, being adopted worldwide as a public health measure. Moreover, scientific evidence has recently consolidated additional actions which are being implemented: the so-called "treatment as prevention", referring to the HIV-positive person receiving ART regardless of his/her own immune status (CD4 T-cells count). That treatment enables the patient to obtain a minimum level of viral copies in the body, situation where the virus is undetectable, significantly reducing the chances of transmission.Evidences indicate a 96% sexual transmission reduction of HIV when the HIV-positive female or male partner has been on ART and has an undetectable viral load. 8,9 Another preventive measure backed up by scientific evidence and adopted by the B...