Purpose: To evaluate tear osmolarity (TO) in patients with epiphora caused by primary-acquired nasolacrimal-duct obstruction (PANDO), before and after an external dacryocystorhinostomy (DCR) and to compare with healthy control subjects.Materials and Methods: Twenty eyes of 20 patients (15 women, 5 men) who suffered from epiphora for at least one year due to PANDO, and 20 eyes of 20 healthy subjects (13 women, 7 men), were included in this study. External DCR was applied to all patients with PANDO, and TO measurements were repeated during the first month follow-up visit after surgery.Results: The mean period for complaints of epiphora was 1.7 0.6 years (1-3). Patients had a mean TO of 282.6 +/- 10 mOsm/l (range: 269-302) prior to DCR, and this increased to 297.7 +/- 7.7 mOsm/l (range: 284-310) one month after DCR (p = 0.0001). Preoperative TO values were significantly lower when compared with the healthy control subjects' (301.7 +/- 10.6 mOsm/l (range: 280-316) (p = 0.0001). No significant differences were detected between postoperative and control group TO values (p = 0.18).Conclusions: Epiphora due to PANDO causes lower TO values. One month after DCR, TO came to similar TO levels when compared to healthy subjects.