OBJECTIVE: To report the clinical characteristics and treatment of subjects with incomitant esotropia following unilateral pterygium excision. METHODS: A retrospective review of 6 consecutive patients who developed incomitant esotropia, limited abduction, and diplopia following unilateral pterygium excision surgery. RESULTS: The mean preoperative deviation was 6 prism diopters (PD) (range, 0-25 PD) in the primary position and 13.8 PD (range, 6-25 PD) in the abducting field of the involved eye. Four patients underwent simultaneous surgery on the conjunctiva-perimuscular connective tissue complex and the medial rectus muscle. One subject had conjunctival-perimuscular connective tissue complex surgery alone. Postoperatively, all patients had orthotropia in the primary position and the deviation in the abducting field was improved to 5.2 PD (range, 0-14 PD). CONCLUSIONS: Incomitant esotropia is an uncommon but serious complication following pterygium excision surgery. Medial rectus muscle recession combined with scar tissue removal is required to eliminate diplopia in the primary position. Conjunctiva-perimuscular scar tissue removal may suffice to improve diplopia in the abduction gaze position.