The authors present three case-histories of patients who were followed up for prolonged periods and where the diagnosis of hypersensitive vasculitis was made. During the follow up period it was not possible to prove development into a different group of vasculitis or to detect a hitherto latent associated disease. Another common sign of the investigated patients was eosinophilia repeatedly found in peripheral blood, bone marrow and tissues. According to clinical criteria the above patients could not be included in groups of known types of vasculitis which are associated with eosinophilia. The patients differed significantly as to clinical manifestations of the disease, the response to different therapeutic approaches and some laboratory immunological indicators. The authors discuss the possible participation of eosinophilia in the tissue damage.