Lymphatic and blood vessel invasion is one of the most important diagnostic and prognostic parameters used by pathologists in the evaluation of neoplastic conditions. Although a variety of tissue artifacts can make the recognition of vascular, capillary, and lymphatic permeation by tumor cells extremely difficult, recent immunohistochemical studies have employed a variety of tissue markers that appear to have great value in establishing the diagnosis of lymphovascular involvement. In the present study, we applied an immunoperoxidase staining technique to previously stained microscopic tissue sections using Ulex europaeus agglutinin I lectin, an endothelial marker that can be used in paraffin-embedded tissues. Our results indicate that this technique can be successfully applied on microscopic slides previously stained with a variety of histochemical stains. It can also be used in those cases in which paraffin blocks are not available or the area in question is absent from the recut tissue sections.