Adult nasolacrimal sac mucocele is an uncommon mass arising in the medial canthal region of the orbit. Twenty-one cases with lacrimal sac mucocele were reviewed retrospectively. We gathered information about the clinical characteristics, natural history, mechanism for mucocele formation and optimal management of this disorder. The results show that the medial canthal mass was confirmed to be dacryocystocele-associated with distal nasolacrimal duct obstruction and proximal obstruction at the junction of the common canaliculus and sac. The interventional procedure of polyurethane stent placement is a practicable and simplified treatment for lacrimal sac mucocele.