Coxsackievirus A16 (CA16) and enterovirus 71 (E71), which cause hand, foot and mouth disease, were compared with respect to their polypeptide composition by PAGE. Only three proteins were resolved for CA16, whereas the four characteristic structural proteins of E71, (VP1, VP2, VP3 and VP4) were separated. The distribution of labeled proteins suggested that the molecular weights of VP2 and VP3 of CA16 were very similar. The smallest protein, VP4, of CA16 and E71 had the same molecular weight, but the other proteins of the two serotypes were different in their molecular weights.