A high-powered argon blue-green laser coupled to a 300-microns quartz fiberoptic catheter was used to create intranasal dacryocystorhinostomy fistulas in fresh-frozen cadaver heads. The procedure, which we term endonasal laser dacryocystorhinostomy, is described. Cadaver specimens were examined postoperatively. Laser rhinostomies were found to involve the posteroinferior portion of the lacrimal sac fossa. Tissues surrounding the fistula site showed no signs of damage. We report on the first patient to undergo endonasal laser dacryocystorhinostomy for the treatment of nasolacrimal duct obstruction, with 10 months of follow-up. We believe endonasal laser dacryocystorhinostomy offers the following advantages over standard external dacryocystorhinostomy: (1) Tissue injury is limited to the discrete fistula site. (2) The cutaneous scar and cosmetic blemish of an external dissection are eliminated. (3) Excellent hemostasis is maintained. (4) Minimal operative and postoperative morbidity permits outpatient surgery, with faster resumption of normal daily activities and increased cost-effectiveness. (5) Patients prefer endonasal laser dacryocystorhinostomy to external dacryocystorhinostomy.