The mechanism of tendon healing is still not fully understood. A dual source of nutrition for the tendon is important at times of injury either from synovial-type fluid bathing the tendon or its own blood supply. In addition, neovascularisation occurs at the site of injury from the time of the insult. The aim of this study was to develop a method of precise endothelial localisation in archived paraffin tendon sections, therefore facilitating the study of the healing of tendons within different species. The sections had to retain a high degree of cytoarchitecture and the stain be of enough contrast to allow quantitative assessment of tendon vascularity in different sites and different species. Endothelial staining was produced using an antibody to the endothelial cell surface marker CD-31 (Dako, Cambridge, UK). The signal was intensified using the Catalytic Signal Amplification kit (Dako). It resulted in a dark brown staining of the tendon endothelium, which was in sufficient contrast to allow automated image analysis.