A large recession of one lateral rectus muscle for exotropia is an infrequently used procedure. In this prospective study, 27 patients (3 to 19 years, mean age of 7) with moderate-angle exodeviation (18-35delta) were treated with large recession (8mm-9mm) of one lateral rectus muscle on their non preferred eye. Initially, there was underaction of the lateral rectus muscle. Within 6 weeks, the lateral rectus muscle regained full abduction, incomitance resolved, and the deviation was eliminated or reduced to a small phoria. Since surgery is confined to the deviating eye alone, operating time, length of anesthesia, and postoperative discomfort is reduced. The average amount of prism diopters needed for correction following operation for 8mm, 8.5mm and 9mm were 20.4delta, 26.4delta, and 31.3delta respectively and esthetically satisfactory results (within 10delta exodeviatior) were obtained in 90.I% of the patients.