Chemical cleavage of the VP6 protein of bovine rotavirus showed that VP6-specific monoclonal antibodies (MAbs) reacted with the amino acid sequence between glycine 48 and asparagine 107. Furthermore, three synthetic peptides (amino acids 48 to 64, 60 to 75 and 91 to 108) containing part of this sequence and 22 consecutive overlapping heptapeptides corresponding to the region between amino acids 48 and 75 were analysed for their immunoreactivity using group-specific MAbs. The MAbs recognized peptides 48-64 and/or 60-75, and a set of overlapping heptapeptides located between residues 53 (asparagine) and 67 (glycine), which have two short sequences in common: IRNW (residues 56 to 59), recognized by MAb RV-133, and (NW)NFD (residues 58/60 to 62), recognized by MAbs RV-50, -1026 and -443. These results indicate that the sequence between amino acid residues 48 and 75 is present in one of the immunodominant sites of VP6.