The purpose of this study was to evaluate relationships between initial and long-term outcome of unilateral recess / resect surgery in adult sensory exotropia, factors associated with long-term outcome, exotropia drift and time to failure follow-up surgery. This was a retrospective study of surgery from 2005 to 2013 for adult patients with at least two years follow-up history. Forty-nine cases were eligible; and 11 were excluded. Median preoperative exotropia was 45PD (25-70) with initial postoperative esotropia of 8PD (exo 8 to eso 30). Mean follow-up was five years, SD 2.5. Fifty percent had successful outcomes at two-year follow-up; i.e. deviation within 10PD of ortho. At final follow-up, 42% had successful outcomes. There was a significant difference for success / non-success groups for preoperative deviation, initial postoperative deviation. Moderate overcorrection gave the best chance of success along with deviations of less than 50PD. The overall rate of exotropia drift at two years follow-up was 8PD/year. Survival analysis showed median time to surgery failure was 24 months. This is useful information when discussing treatment outcomes with patients.