Atazanavir (Reyataz), a protease inhibitor (PI), is approved in many countries for use as a component of antiretroviral therapy (ART) regimens for the treatment of adult, and in some countries in paediatric, patients with HIV-1 infection. ART regimens containing ritonavir-boosted atazanavir improved virological and immunological markers in adult patients with HIV-1 infection, and had similar efficacy to regimens containing lopinavir/ritonavir in treatment-naive and treatment-experienced patients. In addition, unboosted atazanavir was noninferior to ritonavir-boosted atazanavir in treatment-naive patients. Atazanavir is administered once daily and has a low capsule burden. Atazanavir, whether unboosted or boosted, was generally well tolerated and appeared to be associated with less marked metabolic effects, including less alteration of lipid levels, than other PIs. These properties mean that boosted atazanavir, and unboosted atazanavir in patients unable to tolerate ritonavir, continues to have a role as a component of ART regimens in patients with HIV-1 infection.