Children (102) with echovirus 11 infection were analyzed as to symptomatology, which was related to the age of the patients. Neonates manifested an undifferentiated fibrile illness in most cases. The symptomatology of older infants and toddlers was different from that of newborns with respect to presence of discernible pharyngitis in 2/3 of the cases. An exaggerated fibrile response complicated by convulsions or gastrointestinal symptoms was another characteristic feature of this age group. A characteristic manifestation of children more than 3 yr old was pharyngitis which included minute vesicular lesions or exudative ulcers around the fauces.