The complete nucleotide sequence of the mumps virus SP, which was isolated in China, was determined. As with other mumps viruses, its genome was 15 384 nucleotides (nts) in length and encoded seven proteins. The full-length nucleotide sequence of the SP isolate differed from other strains by 4% –6.8% at the nucleotide sequence level. Due to variations of amino acids over the full genome (including the HN and N genes), this isolate exhibited significant variations in the antigenic sites. This report is the first to describe the full-length genome of a genotype F strain and provide an overview of the diversity of genetic characteristics of a circulating mumps virus.