Purpose: We evaluated cultured specimens from silicone tubes removed from patients with congenital nasolacrimal duct obstruction and determined the antibiotic sensitives of the specimens.Methods: This study included 26 eyes of 22 patients who had received endonasal silicone tube intubation for congenital nasolacrimal duct obstruction. The removed silicone tubes were divided into canalicus, lacrimal sac, nasolacrimal duct and nasal cavity parts according to insertion state. Then, bacteria and fungus cultures were performed and rheir antibiotic sensitivity was tested. Results: Bacteria culture rate was 80.8% in the canaliculus and the lacrimal sac, and 88.5% in the lacrimal duct, and the nasal cavity, which was not significantly higher in the nasal cavity than in the nasolacrimal duct and in the nasolacrimal duct than in the lacrimal sac and the canaliculus (p-value < 0.05). The species of cultured Gram-positive bacteria were in the following order: Staphylococcus aureus, streptococcus pneumonia and coagulase negative staphylococcus. Common species of cultured Gram-negative bacteria were Pseudomonas and Serratia marcescenes. All six species of cultured fungi were candida. Among 12 Staphylococcus aureus cultured, eight species showd resistance to methicillin (MRSA). In all patients, the symptomps and the signs of nasolacrimal duct obstruction improved after the tube removal. Conclusions: Bacterial and fungal infection of the silicone tube in patients with congenital nasolacrimal duct obstruction does not appear to affect directly the outcome of silicone tube intubation. Further studies of bacterium and fungi in the nasolacrimal duct before silicone tube intubation are needed for determining the infection causing nasolacarimal duct obstruction J Korean Ophthalmol Soc 2014;55(8): 1121-1125