Virus infection of Aspergillus foetidus was documented over 40 years ago and was one of the first mycovirus infections described in a filamentous fungus. The virus, named Aspergillus foetidus virus (AfV), contains at least two types of icosahedral particles, called AfV-fast (-F) and AfV-slow (-S) virions, based on their relative electrophoretic mobilities. Here, we report the complete nucleotide sequence of the AfV-F genome isolated from virions purified from the prototype isolate of the fungus. The AfV-F double-stranded (ds) RNA genome is tetra-segmented, and the plus strands of each of the four segments, but not the minus strands, are polyadenylated. The organisation and sequences of the four AfV-F dsRNAs are similar to those described for Alternaria alternata virus 1, which we propose is a member of an emerging mycovirus genus ("Alternavirus") and family ("Alternaviridae"), which also includes AfV-F.