The sequence of the gene encoding the major neutralization antigen (VP7) of the type member (bovine virus strain B223) of the proposed serotype 10 of rotavirus has been determined. This was done using a rapid new strategy involving direct sequencing by primer extension of cDNA generated from the relevant virus gene (gene 8) using a combined reverse transcription/polymerase chain reaction. The sequence obtained is 1062 bp in length and contains a single long open reading frame capable of encoding a protein of 326 amino acids. Comparison of the sequence to that of the corresponding gene of the other major virus serotype found in cattle, serotype 6, showed that it was approximately 25% divergent at the nucleotide level and 18% divergent at the amino acid level.