Human immunodeficiency virus (HIV) exploits cell surface receptors to attach to and gain entry into cells. The HIV envelope spike glycoprotein on the surface of virus particles binds both CD4 and a seven-transmembrane coreceptor. These interactions trigger conformational changes in the envelope spike that induce fusion of viral and cellular membranes and entry of the viral core into the cell cytoplasm. Other cell surface receptors also interact with gp120 and aid attachment of virus particles. This review describes these receptors, their roles in HIV entry and their influence on cell tropism.