PURPOSE To determine the value of office nasal endoscopy after dacryocystorhinostomy (DCR). METHODS A prospective clinical observational study of consecutive adult patients after primary external or endonasal surgical DCR, both with intubation for nasolacrimal duct obstruction. Nasal endoscopy was used at the time of tube retrieval and six months after surgery to evaluate nasal pathology and ostium function. RESULTS Sixteen patients were examined. 5/16 (31%) had surgically induced nasal synaechiae; in 2/5 patients transnasal synaechiae occluded the ostium. Granuloma adjacent to the ostia in 2/16 (12.5%) did not impair function. There was no difference in the incidence of synaechiae or granuloma after endonasal compared to external DCR. In 3/16 (19%) endoscopy aided retrieval of tubes concealed by transnasal synaechiae or a narrow nasal space. Six months after surgery ostium function was positive in 12/16 (75%) using the functional endoscopic dye test; 13/16 (81%) patients had relief of epiphora with patent syringing; one had an alternative drainage route. CONCLUSIONS Nasal endoscopy after DCR i) identifies surgically induced nasal mucosal pathology, ii) assists in difficult retrieval of tubes and iii) assesses ostium function using the functional endoscopic dye test. The information obtained is adding much to our understanding of the effects of DCR at the lacrimal / sinus / nasal interface.