The content of the fibronectin, an extracellular glycoprotein in the drainage outflow system of human eyes was determined by the indirect immunoperoxidase staining technique. The degree of fibronectin accumulation in ocular tissues was evaluated by quantitative morphometric analysis. It was shown that the fibronectin level was elevated in the ocular drainage outflow system of humans in ageing and was rapidly increased at different stages of primary open-angle glaucoma development. Increased deposit of fibronectin in trabecular tissues, mainly, in the inner wall of Schlemm's canal and juxtacanalicular, or cribriform part of trabecular meshwork, was demonstrated along with ageing and glaucoma disease progression. A hypothesis underlying the glaucomatous process as an adhesive impairment was proposed.