Though mumps virus (MuV) is a monotypic virus, genetic variation between strains has been described. Viruses have been placed into genotypes designated A-L based on the nucleotide sequence of the small hydrophobic (SH) gene, which is the most variable gene in the mumps genome. Molecular characterisation of MuV is an important component of mumps surveillance because it can help identify the transmission pathways of the virus as well as distinguish between wild-type and vaccine strains. Here, we propose a standardized nomenclature and an analysis protocol for the genetic characterisation of mumps strains to facilitate expansion of molecular epidemiological studies. In addition to assigning standard reference strains for the recognized genotypes of MuV, a convention is proposed for naming for strains and criteria to designate a new genotype.