To analyze the effect of pre-surgical status on the post-surgical stereopsis in surgically aligned adult con-comitant strabismus.By using Titmus and Randot stereo tests,we measured near stereo acuity of 99 adults who had constant exotropia and were successfully aligned by surgery.A covariance analysis showed that the post-surgical stereo acuity was significantly determined by the type of strabismus (i.e.,whether that's intermittent or not;P =0.001),the duration of pre-surgical exotropia (P =0.002)and the year on-set (P =0.048)but not by the pre-surgical deviation (P =0.133).We conclude that the stereopsis of adult concomitant strabismus can be reestab-lished by surgery,while the extent of such an improvement is determined by the type of strabismus,the duration of pre-surgical exotropia and the year on-set of patients.