The aim of this study was to determine the location of elastin in the extracellular material and to estimate the influence of porcine pancreatic elastase-1 (PPE) on the elastin in human trabecular tissue. Trabecular tissues obtained from normal post-mortem eyes and trabeculectomy specimens of primary open angle glaucoma (POAG) were used in this study. The tissues were embedded in Lowicryl K4M and sectioned for electron microscopy. First, the sections were subjected to protein A-gold immunohistochemical staining to determine the location of elastin in the tissues. Second, the sections were exposed to PPE, before immunostaining, to evaluate the change of immunolocalization of the gold particles in the tissue. The results were as follows. In POAG specimens, gold particles indicating the presence of elastin were located in the area of fine fibrillar-like material in the subendothelial layers of Schlemm's canal in POAG specimens. In normal eyes, few gold particles were localized in the area. The density of gold particles in the area was reduced by PPE in POAG specimens. These results show that elastin is localized in the area of fine fibrillar-like material in the subendothelial layers of Schlemm's canal of POAG, and that PPE dissolves the elastin in the area.