In this study the author’s biopsied six eyes of five individuals with recurrent nasolacrimal duct obstruction following a prior dacryoendoscopic probing. All procedures were performed under local anaesthetic, the obstruction or lesion was directly visualised with dacryoendoscope and biopsy was taken with aid of a lacrimal sheath (Argo Cure System Corporation, Toyota, Japan) placed over the dacryoendoscope with the tip protruding 1-2mm over the tip of the scope. The biopsy specimen was scraped from the wall of the nasolacrimal duct. The histology of biopsy tissue demonstrated stratified epithelium with infiltration of inflammatory cells in the subepithelial connective tissue. Immunohistochemistry showed Cytokeratin (CK) 4 and 13 positive cells in epithelial tissue of recurrent disease and mucin 5AC (MUC5AC) cells were also found. The authors feel this suggests squamous metaplasia from persistent inflammation, whereas the specimens were negative for Loricrin, transglutaminase and PAX6. Loricrin and transglutaminase are keratinisation associated proteins and the authors infer their absence suggest the recurrent obstruction is not a keratinising process. The authors acknowledge the limitations such as small sample size; the polarity of tissue could not be determined and that the pathology of recurrent obstruction could be different to the primary obstruction. They feel the biopsy technique is unsuitable for primary acquired nasolacrimal duct obstruction as the obstruction generally tears when the sheath is pushed through the lesion. As the dacryoendoscopic equipment is not widely used outside Japan it would be difficult to replicate the study in other parts of the world.