Ostium closure due to local reparative processes is the most common cause of recurrence after endoscopic endonasal dacryocystorhinostomy (DCR), but as yet poorly studied. Aim - to perform morphological study of reparative processes at osteotomy site after endoscopic endonasal DCR. Material and methods. The study included 18 patients (18 women) aged 62.59±10.07 years with nasolacrimal duct obstruction, who underwent endoscopic endonasal DCR (P.J. Wormald modification). Osteotomy site biopsies were taken on days 2, 5, 7, 10, 14, 21, 28, and 60 after the surgery. All the samples were stained with haematoxylin and eosin. For further details on cellular composition of inflammatory infiltrate, 54 samples were also processed into semi-thin sections. The slides were then viewed under Leica DM-2500 (Leica, Germany) photomicroscope. Leica DFC320 digital camera and ImageScope Color software were used for image acquisition and analysis. Results. Morphological examination revealed the predominance of inflammatory cells in biopsy material on day 1 after DCR. On day 14, the number of cells would usually be reduced indicating the completion of the exudative phase of inflammation. Since then, activated fibroblasts prevailed over the rest of cellular elements. Twenty eight days after DCR, proliferating fibroblasts and collagen fibers were present. Sixty days after the surgery, fibrillar component prevailed over cells and showed compaction. Conclusion. Our results demonstrate that the reparation process nears completion before day 60 after the surgery. A series of morphological examinations of biopsy material from osteotomy sites has revealed individual features of reparation in nasal and lacrimal sac mucosa after endoscopic endonasal DCR.