The arginine-glycine-aspartic acid motif at the C terminus of coxsackievirus A9 capsid protein VP1 has been shown to play a role in specific attachment of the virus to alpha(v)beta3 integrin on the host cell surface. The C-terminal region of the VP1 protein has also been shown to be highly antigenic by using peptide scanning techniques. To find out whether this region contains a neutralizing epitope, three overlapping peptides covering the C-terminal end of VP1 were synthesized and rabbit antisera were raised against these peptides. Neutralization of the virus was observed with all three antipeptide antisera in A549 cells and with two antisera in RD cells.