Objective To evaluate the effect of intraoperative mitomycin C on the stability of refraction after laser-assisted subepithelial keratomileusis (LASEK) in treating high myopia.Methods In this prospective control study,66 eyes of 33 patients were divided into two groups.One eye of each patient was treated with 0.02％ mitomycin C (MMC) during LASEK for myopia (MMC group) while the other eye was not treated (control group).Corneal refraction,intraocular pressure using noncontact tonometry and haze were measured at 3,6,9,12 and 15 weeks after LASEK,and the two groups were compared using paired t test.Results The difference in refraction between the 3rd week and the 6th week in the MMC group was statistically significant (t=2.254,2.175,P＜0.05),while the differences between the other adjacent time points were not statistically significant.Refraction in the MMC treatment group became stable at 9 weeks after surgery.In the control group,the refractive differences between the 3rd and 6th weeks and the 6th and 9th weeks were statistically significant (t=3.315,2.440,2.356,P＜0.05),while the differences between the other times were not significant.Refraction in the control group became stable 12 weeks after surgery.The average course and frequency of using 0.1％ fluorometholone eye drops after surgery in the MMC group were 9 weeks and 2.6 times per day while course and frequency were 12.9 weeks and 2.9 times per day for the control group.Conclusion Intraoperative MMC can shorten the refractive fluctuation time after LASEK for treating high myopia.The effect may reduce the frequency and dosage of corticosteroid eye drops after surgery and avoid the occurrence of steroid-induced ocular hypertension and glaucoma.