Ectropion is the most frequent eyelid malposition, characterized by the eversion of the margin and exposure of the conjunctiva and the cornea. It is classified as congenital (primary and secondary) and acquired (involutional, paralytic, mechanical and cicatricial). Congenital ectropion is rare and it is usually associated with other malformations such as euryblepharon, ptosis, epicanthus inversus, and blepharophimosis syndrome. Involutional ectropion is the most frequent form of acquired eyelid eversion and a result of multiple factors. The mechanisms involved in its pathogenesis are discussed in this review. Cicatricial ectropion is caused by the shortening of the anterior lamella of the lid, secondary to congenital malformations, trauma, burns, skin conditions, scarring skin tumors, medications, allergies, blepharoplasty complications, and involutional changes that result in loss of skin elasticity. Mechanical ectropion is caused by eyelid tumors or inflammatory disorders that cause orbicularis spasm. The evaluation of the patient, selection of treatment and surgical techniques are described in detail.