There is limited evidence in literature determining age effect on outcomes of endoscopic dacryocystorhinostomy (EDCR) in adult patients with primary acquired nasolacrimal duct obstruction (NLDO). We aimed to analyze the outcomes of EDCR according to age in primary acquired NLDO. A retrospective study was performed on consecutive adult patients and patients were divided into two age groups; group 1 (aged to 61 years) and group 2 (aged 62 to 89 years) based on the average value. The minimum required follow-up period was 6 months. A total of 441 EDCRs performed in 342 patients were enrolled. The anatomical success rate was not significantly different between the two groups (91.8% and 88.2%, P = 0.209). However, the functional success rate was significantly lower in the group 2 (85.1% and 76.9%; P = 0.036). Functional failure was associated with old age and a history of diabetes mellitus (P = 0.024 and P = 0.008). In subgroup analysis of patients with anatomical success but functionally failed EDCR, group 2 had significantly more comorbid conditions such as eyelid laxity (P = 0.026). In conclusion, the comorbid conditions which increase with age may affect functional outcome, especially eyelid laxity, careful preoperative examination of the eyelid and conjunctiva should be emphasized to lacrimal surgeons before performing EDCR.