Despite the availability of several approved drugs for the treatment of human immunodeficiency virus (HIV) infection, the limited effectiveness of current antiretroviral regimens, mainly due to the emergence of resistance, makes the development of new agents necessary. Several novel compounds are being added to existing classes, but newer classes of antiretroviral drugs, such as HIV entry inhibitors, are also under development. Maraviroc is a novel small molecule that specifically antagonizes the chemokine CCR5 receptor required for efficient HIV entry. It displays potent and broad-spectrum anti-HIV activity and excellent pharmacokinetic and safety profiles. All these features and the promising results obtained in early clinical trials make this agent a good candidate for inclusion in combination therapies for HIV treatment. Maraviroc is the most clinically advanced CCR5 antagonist and has just entered phase III clinical trials.