Endoscopic intranasal dacryocystorhinostomy has been used as a primary treatment of lacrimal obstruction and for revision of conventional dacryocystorhinostomy. This study correlates dacryocystographic anatomy with the success of the endoscopic surgical technique. Eighteen patients with epiphora and nasolacrimal obstruction underwent operations. Preoperative dacryocystography identified 11 patients with either normal or enlarged lacrimal sacs, and seven patients with cicatrized lacrimal sacs. Patients with lacrimal sac stones and tumors were excluded. Endoscopic intranasal dacryocystorhinostomy was successful in nine of 11 (82%) patients with normal or enlarged lacrimal sacs, and in two of seven (29%) patients with cicatrized lacrimal sacs. The endoscopic technique was much more successful with normal or enlarged lacrimal sacs than with cicatrized lacrimal sacs (P = .049). Lacrimal sac anatomy as determined by preoperative dacryocystography is an important prognostic factor in technically achieving surgical success.