Objective: To determine the prevalence of lacrimal sac pathology in patients undergoing dacryocystorhinostomy (DOR) for primary acquired nasolacrimal duct obstruction (PANDO). Design: Observational. case series. Participants. One hundred sixty-six patients with! symptoms of PANDO. Methods: A total of 202 lacrimal sac biopsies were obtained from 166 patients undergoing external DCR procedures for symptoms of PANDO. Main Outcome, Measures; Patient demographics, presenting symptoms and signs, relevant history, and assessment of the nasolacrimal system were recorded. All lacrimal biopsy specimens were examined histopathologically. Results. A total of 1181 patients (71%)were female and, 48 patients (29%) were male. The mean age was 60.7 years (range, 21-93 years). All patients demonstrated epiphora, and 32 patients had dacryocystitis. Duration of symptoms ranged from 6 weeks to 50, years. No, lacrimal sac tumors were detected. Sixty-five percent of specimens demonstrated chronic, inflammation. Conclusions: No neoplasms, were detected among 202 lacrimal sac specimens from 166 patients with symptoms, of PANDO. Most lacrimal sac specimens, demonstrated chronic inflammatory changes. We conclude that a lacrimal sac biopsy should be performed when there is suspicion of a neoplasm based, on the clinical, historical, or intraoperative findings, rather than. routine biopsy of all patients with PANDO. Ophthalmology ; 108:2038-2040 (C) 2001 by the American Academy of Ophthalmology.