The cause of acquired lacrimal drainage obstruction may be primary or secondary. Primary acquired nasolacrimal duct obstruction results from inflammation of unknown cause that eventually leads to occlusive fibrosis. Secondary acquired lacrimal drainage obstruction, the theme of this report, may result from a wide variety of infectious, inflammatory, neoplastic, traumatic, or mechanical causes. An etiologic classification system for acquired lacrimal drainage obstruction is proposed, and it is illustrated by representative patients from the author's practice and discussed with reference to published reports.