AIM: To investigate the clinical outcomes of different intubation techniques in the cases of failed primary probing. METHODS: This retrospective study was performed on 338 patients with the diagnosis of congenital nasolacrimal duct obstruction with age 1-4y that had failed primary probing. Intubation was performed under light sedation in operating room and the stent was left 3mo in place. Clinical outcome was investigated 3mo after tube removal. RESULTS: Bicanalicular intubation method had higher complete and relative success rates compared to monocanalicular intubation (P=0.00). In addition, Monoka intubation had better outcomes compared to Masterka technique (P=0.046). No difference was found between genders but the higher the age, the better the outcomes with bicanalicular technique rather than monocanalicular. CONCLUSION: Overall success rate of bicanalicular intubation is superior to monocanalicular technique especially in older ages. Also, based upon our clinical outcomes, Masterka intubation is not recommended in cases of failed probing.