Dacryocystitis is an infection of the lacrimal sac, secondary to obstruction of the nasolacrimal duct at the junction of lacrimal sac. The term derives from the Greek dákryon (tear), cysta (sac), and -itis (inflammation). It causes pain, redness, and swelling over the inner aspect of the lower eyelid and epiphora. When nasolacrimal duct obstruction is secondary to a congenital barrier it is referred to as dacryocystocele. It is most commonly caused by Staphylococcus aureus and Streptococcus pneumoniae. The most common complication is corneal ulceration, frequently in association with S. pneumoniae. The mainstays of treatment are oral antibiotics, warm compresses, and relief of nasolacrimal duct obstruction by dacryocystorhinostomy.