Anti-Viral agents are drugs in that prohibit the spread of virus by preventing the replication of the genome, obstructing the entry of viruses into the host cells, or by inhibiting viral protein synthesis and/ or viral assembly. Antiviral drugs, unlike antibiotics, do not destroy their target; rather they only inhibit their development. Antivirals are of 2 types- Narrow spectrum (treating for specific viral infections) and broad spectrum (treating wide range of similar viral infections). These antivirals, for now are available to treat only few viral infections. Most clinical useful antiviral agents exert their action on viral replication, either at stage of nucleic synthesis or at stage of slow protein synthesis and processing. Antiviral drugs are designed in such a way that these drugs identify viral proteins, or parts of proteins, that can be disabled.