Atopic dermatitis is associated with immunoregulatory abnormalities similar to those observed in acute Kawasaki disease. We investigated whether the prevalence of atopic dermatitis is increased among children who acquire Kawasaki disease. In a case-control telephone survey 83 Kawasaki disease patients and 83 children with innocent heart murmurs were matched for age and time between clinic visit and interview. The interviewer was blinded to the hypothesis of the study. Nine (11%) Kawasaki disease patients but only one (1%) unaffected child had atopic dermatitis; the incidence of atopic dermatitis among children with Kawasaki disease was 9 times greater than that of controls (95% confidence limits, 1.6 to 49.4). Serum immunoglobulin E concentrations were significantly higher (P = 0.02, Mann-Whitney) in 44 unselected Kawasaki disease patients (median, 22; range, less than or equal to 4 to 900 IU/ml) studied 6 to 12 months after onset than in 27 children of similar age (median, less than or equal to 4; range, less than or equal to 4 to 164 IU/ml). We observed that there is a strong association between atopic dermatitis and Kawasaki disease.