The development of resistance to all currently marketed drugs for HIV infection has been observed and is a major reason for failure of therapy. In particular, there is a great need for drugs against new targets and having novel mechanisms of action against new targets. Most of the currently approved drugs are targeted toward the inhibition of viral enzymes. However, the process of viral entry and fusion has become an active area of research. Among the steps involved in viral entry, binding of HIV to CD4 co-receptors on the cell surface is an important and promising target for new drug development.