A number of studies have documented the reasonable efficacy and safety of radial keratotomy, but most based upon results obtained in low or moderate myopia or short term follow up after surgery. We complied 5 year and longer follow up data on 91 consecutive radial keratotomy surgeries on high myopia (over -6.00 diopters) performed by one surgeon 5 year-follow up was obtained on 21 (23%) of these eyes. The mean spherical equivalent before surgery was -11.02 diopters (D), the average keratometry value was 44.40 D, and all of the eyes had an uncorrected visual acuity of 0.04 or less. The average change in spherical equivalent was 3.44 D for eyes examined at 1 year, compared with 3.05 D for eyes at 3 years and 2.87 D at 5 years after surgery. Average keratometry value were 42.30 D at 1 year, 41.60 D at 3 years, and 41.30 D at 5 years after surgery. In our study, the decrease in spherical equivalent of 0.57 D was statistically significant (P < 0.05), as was the reduction in average keratometry value of 1.00 D. The effect of the surgery on spherical equivalent continued to regress through all the 5 years of follow up. However, the keratometric measurement decreased up to 5 years which indicated progressive flattening of the cornea. Also we divided these eyes into 2 groups, lower-myopic group (-6.00 D~-9.75 D) and higher-myopic group (over -10.00 D). In each category, the changes in spherical equivalent were 3.60 D, 2.21 D at 5 years, compared with 3.65 D, 3.25 D at 1 year respectively. The efficacy of radial keratotomy was lower, and the change of spherical equivalent between 1 year and 5 years was larger in the higher-myopic group than in the lower-myopic group. The results show that both radial keratotomy effectiveness and long term stability decrease in higher myopic cases.