Immunohistochemical techniques are a convenient method to identify the cells responsible for the production of MMPs and TIMPs in local tissues under pathophysiological conditions. Direct and indirect methods are presented for immunohistochemistry, but the latter is usually utilized for the staining of MMPs and TIMPs because it is more convenient and sensitive than the former. Specific recognition of the MMP and TIMP species by the primary antibody which has no cross-reactivity with other molecules is essential for immunohis-tochemistry, and thus monoclonal antibodies are considered to be suitable for the purpose. In this chapter, immunohistochemistry using commercially available primary monoclonal antibodies against human MMPs and TIMPs is described. Human tissue samples obtained at surgery are fixed with periodate-lysine-paraformaldehyde (PLP) fixative, embedded in paraffin wax, and paraffin sections are immunostained according to the avidin-biotin-peroxidase complex (ABC) and/or immunogold-silver staining (IGSS) methods. Treatment of the tissues with monensin prior to fixation may be necessary to augment intracytoplasmic staining especially in mesenchymal tissues, but not in carcinoma tissues. Common problems during immunostaining are also given with a practical guide.