The prevalence of atopic dermatitis increased markedly in the period 1960s to the 1990s. Earlier findings indicate that infections acquired in early life enhance or suppress the expression of atopic disease as a result of a change in immune reactivity. Our objectives were to examine the association between measles, mumps and rubella vaccination, measles infection and the risk of atopic dermatitis. A random sample of 9,744 children were followed up from birth to 3-15 years. Their parents responded to a questionnaire including highly structured questions on atopic dermatitis, measles, mumps and rubella vaccination and measles infection. Information on parental educational level was obtained from Statistics Denmark. The cumulative incidence of atopic dermatitis at age 14 was 19.7%. The confounder adjusted incidence ratio of atopic dermatitis among measles, mumps and rubella vaccinated children versus children not subjected to measles, mumps and rubella vaccination and measles infection was 1.86 (95% CI 1.25-2.79); the incidence ratio for measles-infected children was similar. The incidence of atopic dermatitis increased after measles, mumps and rubella vaccination and measles infection, which is surprising in view of the hygiene hypothesis. We suggest further study of the possible short-term and long-term effects of virus and bacteria on the immune responses and expression of atopic disease.