Five young children (mean age 26.4 months) with angiolymphoid hyperplasia with eosinophilia (Kimura's disease) from either the upper arm or buttock were identified over 18 months. The unusual distribution of the lesions and the young age of the patients suggested a possible association with immunisation. The clinical and histopathological features in these cases were accordingly reviewed. The biopsy specimens showed the usual histological appearances of a prominent inflammatory component, fibrosis, and vascular proliferation associated with aggregates of eosinophils. The features were those of a reactive rather than neoplastic process. Immunohistochemical preparations showed positive staining of variable numbers of plasma cells with antibodies to IgG, IgM, IgA and IgE and a reticular staining of germinal centres with IgM and IgE antibodies. Immunisation histories obtained from the patients' general practitioners showed a remarkable correlation between the distribution of the lesions and the sites of injections and an aetiological role for immunisation in these cases seems likely.