AIM: To evaluate the moderate-term success and calculate the mean dose-effect ratio in large-angle esotropic patients who underwent three muscle surgery. METHODS: In a retrospective study, we reviewed the medical records of 37 patients with large-angle esotropia who underwent bilateral medial rectus recession and one lateral rectus resection. Sex, age at surgery time, amount of recessed or resected muscles in millimeter (mm), pre- and postoperative alignment in prism diopter (D), dose/response ratio, and presence of amblyopia and other associated vertical deviations were recorded. RESULTS: The mean age of subjects at surgery was 12.2±12.3y (range: 1-57). The mean preoperative deviation of 70.4±8.1 D (range: 60-85 D) decreased to a mean of 5.4±8.1 D (range: 0-30 D) postoperatively (P<0.005). Successful alignment was achieved in 30 of 37 patients (81%) at a mean follow-up of 15.7±20.1mo (range: 3-90). The mean amount of recession and resection was 17.59±1.29 mm, and a mean dose-response ratio of 3.79±81 (range: 2.83-4.66) was determined. CONCLUSION: Three-muscle surgery for large-angle esotropia results in good moderate-term outcomes without high rates of overcorrection or undercorrection.