AIM:To analyze the pathogenic bacteria and drug sensitivity in cases of dacryocystitis secondary to congenital nasolacrimal duct obstruction（CNDO）. METHODS:Bacterial cultures and drug sensitivity tests were conducted for the lacrimal sac secretion from the 98 cases (110 eyes) with CNDO. RESULTS:Totally 155 bacterial strains were isolated from lacrimal sac secretion in 94 eyes, and the pathogenic bacteria positive rate was 85.5%. The bacteria positive rates of Gram positive cocci and Gram negative bacilli were 65.8% and 23.9%, respectively. 94.2% of all isolated strains were sensitive to levofloxacin. CONCLUSION: Drug sensitivity test showed that the vast majority of bacteria had high sensitivity to levofloxacin. New quinolone antibiotic eye drops are applicable to dacryocystitis secondary to CNDO.