Objective: To determine the success rate of probing for congenital nasolacrimal duct obstruction (CNLDO) according to the age at probing and to evaluate the other factors affecting the success rate of probing. Material and Methods: The records of patients who underwent probing with the diagnosis of CNLDO between January 2010 and December 2019 in Ankara University Faculty of Medicine Department of Ophthalmology were assessed retrospectively. The patients were divided into 4 groups based on their age at probing as 12-18 months, 19- 24 months, 25-48 months, and after 48 months. Successful probing was documented as remission of watering complaints, absence of epiphora and reflux from the punctum when pressed on the sac area in the examination 2 weeks after the procedure. Results: A total of 206 eyes of 177 patients were included in the study (85 female and 92 male). The mean probing age was 28.14±14.56 months (12-61 months). The success rate of probing surgery was found to be 88.8% for all patients. The success rate was 91.4% in 12-18 month-olds (n=58); 91.1% in 19-24 montholds (n=45); 88.2% in 25-48 month-olds (n=85); and 77.8% in over 48- month-olds (n=18). Although the success rate was found to be lower in those who had probing at over 48 months, the difference between the groups was not statistically significant (p=0.41). We found that gender (p=0.26), age at probing (p=0.25), or bilaterality (p=0.63) were not effective, but having conjunctivitis or chronic dacryocystitis (p=0.004), and to aspirate fluorescein from the nose after probing were effective on surgical success (p˂0.001). Conclusion: Although the success rates look to be decreasing slightly with age, probing of the nasolacrimal duct is a safe and viable procedure for children under 5 years of age with CNLDO with high success rates.