This study aimed to evaluate the effect of botulinum toxin (BT) on the amount of deviation and fusional control state of intermittent exotropia. Twenty-one patients (five male and 16 female) aged five to 18 years with progression of exotropia were recruited. Each had reduced fusional control and an increased Newcastle control score (≥3). BT of 10 units Dysport was given to the lateral rectus muscles. A minimum follow-up of six months was allowed. The Newcastle control score increased significantly over follow-up. Stereoacuity improved from 224.6 ±278.9” pre-treatment to 100 ±100.3” post treatment. The near angle of deviation reduced from 26.4 ±10.1 to 1.8 ±10.3PD and the distance angle of deviation reduced from 30.9 ±7.1 to 11.8 ±14.4PD. Binocular alignment within 10PD was achieved by 38.1% at distance fixation. Mild ptosis was documented in nine patients (42.8%). The authors propose this to be a promising treatment.