HIV requires binding to both the CD4 molecule and a coreceptor to enable entry into the cell. CCR5 is a chemokine receptor that is utilized as a coreceptor by the majority of virus in early asymptomatic HIV infection. Maraviroc is a novel small molecule CCR5 antagonist which, in Phase IIb/III clinical trials up to 48 weeks, has been shown to be efficacious as part of an optimized antiretroviral regimen against CCR5 tropic HIV-1 in treatment-experienced patients. A further trial has demonstrated its noninferiority to efavirenz in achieving a HIV viral load less than 400 copies/ml as part of highly active antiretroviral therapy in treatment-naive individuals. It has recently received regulatory approval for use in North America and Europe in treatment-experienced patients. With increasing use, the role of maraviroc in the treatment of HIV-infected patients will be more clearly defined.