Antibodies to Epstein-Barr-virus-specific DNase in children under 15 years old from Taipei, Taiwan were determined by an enzyme neutralization test. Serum was taken as positive for the anti-DNase antibody when 1 ml of serum could neutralize > or = 2 units of the DNase activity. Among the 1,292 sera tested, 5.6% of the children were shown to have anti-EBV DNase antibodies, a result similar to that for adults. Maternal antibodies against the EBV DNase were found to decrease very rapidly 2 months after the child's birth, and new antibody appeared upon natural EBV infection.