These are tables of the clinically most importantviruses. A vast number of viruses cause infectious diseases, but these are the major ones^{[citation needed]}.

Basic structural characteristics, such as genome type, virion shape and replication site, generally share the same features among virus species within the same family. There are currently 21 families of viruses known to cause disease in humans.

There are five double stranded DNA families: three are non enveloped (Adenoviruses, Parvovirus and Polyomavirus) and two are enveloped (Herpesvirus and Poxvirus). All the non enveloped families have icosahedral nucleocapsids.

There is one family of partly double stranded DNA viruses: the Hepadnaviridae. These viruses are enveloped.

There is one family of single stranded DNA viruses that infect humans: the Parvoviridae. These viruses are non enveloped.

There are seven positive single stranded RNA families: three non enveloped (Astrovirus, Calicivirus and Picornavirus) and four enveloped (Coronovirus, Flavivirus, Retrovirus and Togavirus). All the non enveloped families have icosahedral nucleocapsids.