Fever was a common symptom in patients with Human Immunodeficiency Virus (HIV) infection in the early phases of the epidemic. Fever of Unknown Origin (FUO) was frequent in HIV-patients and conditions causing FUO were often opportunistic conditions. The HIV-epidemic continues to expand, but access to effective antiretroviral therapy is also expanding, resulting in a growing number of HIV-infected patients less likely to be severely immunocompromised and less likely to present opportunistic conditions. Yet part of newly diagnosed patients continue to present with advanced HIV-infection and are still at high risk of opportunistic conditions. This epidemiological evolution strongly influences the spectrum of conditions causing fever and FUO in HIV-patients. While some patients with HIV-associated fever and FUO may still be suffering from opportunistic conditions classically associated with HIV-related FUO, many others will have causes of fever that are similar to the non-HIV-infected population or to classical FUO. Strategies for diagnosis and treatment of fever and its causes in HIV-infected patients need to take into account this evolution.