The relationship between the disorder known in Japanese and Chinese literature as Kimura's disease and that known in Western literature as angiolymphoid hyperplasia with eosinophilia (ALHE) has been the subject of debate. Many reports have used the terms synonymously. We have reviewed the histological and clinical features of 4 cases, all occurring in Caucasians, 2 of which are typical of Kimura's disease and 2 of ALHE. Analysis of the cases indicates that the histological features of the 2 disorders are sufficiently different to warrant their recognition as 2 distinct entities. The histological and clinical features of Kimura's disease are most consistent with an allergic or autoimmune process in which blood vessels, lymphocytes and eosinophils participate. Those of ALHE suggest a primary, probably neoplastic disorder of vascular endothelium with a variable and secondary inflammatory response. Although there is some clinical overlap between patients with the 2 disorders, the histological features are distinctive, and the 2 terms should not be used synonymously.