Purpose. To report long-term visual and refractive results of small-incision lenticule extraction (SMILE) in treatment of high myopia. Materials and Methods. Medical records of patients who underwent SMILE for surgical correction of myopia or myopic astigmatism were retrospectively reviewed. Only patients with a preoperative spherical equivalent of subjective manifest refraction (SE) >= 6D and a postoperative follow-up of 5 years were included in the study. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and SE were analyzed preoperatively and at 1-, 3-, and 5-year postoperative periods. Results. Thirty-seven eyes of 37 patients were included in the study. The mean attempted SE was -7.47 +/- 1.10 D (range -6.00 to -10.00 D). At the 5-year visit, the mean difference between achieved and attempted SE was -0.43 +/- 0.47 (0.50 to -1.25 D). Mean postoperative UDVA and CDVA were 0.20 +/- 0.18 and 0.06 +/- 0.08 logMAR, respectively. At the 1- year visit, 70% and 97% of the eyes were within +/- 0.50 D and +/- 1.00 D of the intended correction. At the 5-year follow-up, 59% and 92% percent of the eyes were within +/- 0.50 D and +/- 1.00 D of the intended SE, respectively. At the 5-year visit, the efficacy index was 0.89 +/- 0.26 and the safety index was 1.16 +/- 0.20. Fifty-four percent of the eyes gained one or more lines of CDVA. Conclusion. SMILE with an intended correction of up to a spherical equivalent of 10 D is safe and effective. However, there is regression of the refractive effect over extended follow-up.