Brazil provides free antiretroviral (ARV) therapy to some 150,000 individuals living with HIV/ AIDS). ARV regimens require optimal adherence to achieve undetectable viral loads and to avoid viral resistance. Physicians play a key role to foster ARV adherence, but until now little is known about the communication between physicians/ people living with HIV/AIDS in this setting. In-depth interviews were conducted with 40 physicians treating people living with HIV/AIDS at six public reference centers in Rio de Janeiro, Brazil. Interview topics included: experiences in the treatment of people living with HIV/AIDS, relationship and dialogue with patients, barriers/facilitators to adherence, and effectiveness of available services. Barriers to ARV adherence were mainly related to the low quality of patient-provider relationship. Other barriers were related to "chaotic" patients' lifestyles, and inadequate knowledge and/or negative beliefs about HIV/AIDS and ARV effectiveness. It is necessary to improve networking between services, establish agile referral systems, and improve health professionals' integration. These structural changes could contribute to improved adherence, resulting in improved quality of life for people living with HIV/AIDS.