The authors report two cases of postoperative lagophthalmos immediately following ab externo dacrycystorhinostomy (DCR). Two female patients, aged 67 and 62 years, underwent under general analgesia for chronic dacryocystitis with mucocele. An inferior surgical approach, sparing the inner canthal ligament was chosen in both cases. Lagophthalmos was observed on the operated side on the first postoperative day. Normal lid occlusion was present on the contralateral side. Impairement of palpebral occlusion was predominant in the nasal portion of the lid fissure. Upon voluntary and reflex blinking, a reduction in the downward movement of the superior lid was observed. This reduction was not as apparent when the patients were asked to produce a forced blink. Lagophthalmos disappeared progressively over 3 postoperative months in both cases. Neither epiphora nor any corneal complications were observed. Lagophthalmos following DCR via an inferior approach is a previously unreported complication and may be related to the disinsertion of the nasal portion of the orbicularis muscle and periosteum at the time of periosteal cleavage. Recovery of normal lid function may be due to reattachment of the periosteum.