Because parvovirus B19 occasionally causes some of the features typical of Kawasaki disease, we investigated B19 involvement in 15 children with Kawasaki disease. Active or recent B19 infection, as shown by B19-DNAaemia, positive B19-specific IgM antibodies, or both, was diagnosed in 10 patients (67%). A high frequency of all major criteria for diagnosis of Kawasaki disease (60%), anaemia (60%), coronary aneurysms (30%), and arthropathy (30%) was found in children with B19-associated Kawasaki disease. Thus B19 may have a pathogenic role in the development of Kawasaki disease, with other predisposing factors.