The medical records of 33 consecutive patients who developed secondary exotropia following surgery for esotropia were reviewed. Only six patients (18%) had normal medial rectus function. Lateral rectus recession proved to be an excellent procudure for correcting the deviation in these patients, provided the surgery was limited to the eye with the narrower palpebral fissure. Twenty-seven patients (82%) exhibited limitation of adduction secondary to medial rectus underaction. Of these patients, 75% were successfully corrected following a 12 mm advancement and resection of the underacting medial rectus muscle. The details of the surgical technique performed are discussed.