The importance of estrogen in vascular neoplasia is suggested by a predilection for women and a tendency for rapid growth during pregnancy. Although early experiments using radioligand assays demonstrated estrogen receptor (ER) expression, these findings were not confirmed by subsequent immunohistochemical studies which were performed with antibodies raised against ER alpha. A newly discovered estrogen receptor subtype, ER beta, has not been previously characterized in vascular lesions. In order to verify the expression of estrogen receptors in vascular neoplasms as well as to clarify the inconsistency between radioligand and early immunohistochemical studies, we examined a series of 53 benign and malignant vascular neoplasms for ER beta expression. All of the subtypes of vascular neoplasia examined had nuclear expression of ER beta. The majority of cases (94%) displayed 2+ to 3+ staining. The discrepancy between radioligand studies and previous immunohistochemical studies is attributable to the use of antibodies raised against ER alpha, which is not expressed in vascular lesions, and not ER beta, which is broadly expressed in both benign and malignant vascular neoplasms. Although ER beta may be of limited diagnostic use in vascular neoplasia due to its broad expression, the potential exists for a therapeutic approach using ER agonists.