Megabirnaviridae is a family of double-stranded RNA viruses with one genus Megabirnavirus which infects fungi.

There is only one species in this family: Rosellinia necatrix megabirnavirus 1.

Diseases associated with this family include: reduced host virulence.

[2][3] Viruses in the family Megabirnaviridae are non-enveloped, with icosahedral geometries, and T=1 symmetry.

[citation needed] The genome is composed of two double-stranded RNA segments of 7.2–8.9 kbp each and of a total length of 16.1 kbp.