In a 29 year old patient suffering from complete posttraumatic obstruction of the lacrimal system a PTFE-vascular graft was implanted as a bypass between conjunctival and nasal mucosa. The bypass was patent and well tolerated for 2 1/2 years before it had to be removed because of a therapy refractive naso-cutaneous fistula. Light- and electronmicroscopy of the explanted material showed an accumulation of inflammatory cells and fibrovascular tissue growing into the internodal spaces from both the outer and luminal surface. Numerous activated macrophages, the phagosomes containing amorphous material of different, partly fibrillary shape presumed to be degraduated PTFE, could be detected. The smooth inner surface was not covered by epithelial cells.