AIM: To compare the success rates of probing for the treatment of congenital nasolacrimal duct obstruction in children divided into three age groups. METHODS: One hundred and eighty children with uncomplicated congenital nasolacrimal duct obstruction underwent probing in Eye Hospital of Liaquat University of Medical and Health Sciences Hyderabad, Sindh, Pakistan from March 2005 to January 2008. The children were divided into three groups: Group I (aged 4-6 months), Group II (aged 7-12 months) and Group III (aged 13-24 months). Success was defined as complete resolution of signs and symptoms. The chi-square test was used to analyze the results. RESULTS: The success rate was 100.0% in Group I, 88.5% in Group II and 82.3% in Group III. The overall cure rate for the entire study was 90.7%. CONCLUSION: The efficacy of probing decreases with the increasing age. However, when probing is done within six months of age, it is highly effective and results in complete resolution of symptoms.