Purpose:The purpose of this study was to evaluate the role of probing in congenital nasolacrimal duct obstruction in children age 2 years and older and to establish factors predictive of the outcome.Materials and Methods:A prospective study was conducted on consecutive patients older than 24 months with congenital nasolacrimal duct obstruction. All patients were treated with a simple nasolacrimal duct probing as primary treatment. Outcome measures included an ophthalmologic examination plus a parental history of residual symptoms at one and 6 months after surgery.Results:A total of 82 children with a mean age of 34.5 months (range, 24 months to 60 months) underwent nasolacrimal duct probing. The complete response rate was 54%. Partial response and failure were observed in 25% and 20.8% of the eyes, respectively. Bilateral obstruction was associated with failure of probing (P = 0.007, Odds Ratio: 5.76). However, age older than 36 months was not associated with the failure rate.Conclusion:Primary probing maintains a high success rate without any age related decline in congenital nasolacrimal duct obstruction.