Forty patients with infantile esotropia were treated by one ophthalmologist and followed up for 5 to 14 years. In all cases the initial surgery was performed by the age of 2 years, 4 months. The angle of deviation was reduced to within 10 prism diopters of orthotropia in 34 patients, and in 26 of them the reduction was maintained. However, only 6 of the 26 with a stable reduction showed evidence of binocular function by both troposcopic evaluation and the Wirt stereo test. Dissociated vertical divergence, nystagmus and amblyopia were much more common among the patients in whom fusion did not develop and may be the cause of this failure.