In situ myopic keratomileusis was performed in 30 eyes of 17 patients to correct high myopia. Mean follow-up was 460 days. Mean preoperative myopia was -15.66 D. The mean myopic decrease was 13.34 D, 85% of the total presurgery myopia. Postoperatively, 8 eyes (27%) were within ± 1.00 D; 19 eyes (63%) within ± 2.00 D; and 27 (90%) were within ± 6.00 D. Preoperatively, 10 eyes (33%) had 20/40 or better visual acuity with spectacle correction. Postoperatively, 2 eyes (7%) had 20/40 or better without correction. Four eyes lost 2 or more Snellen lines of spectacle corrected visual acuity. Many eyes had an improved corrected visual acuity. The major complications were tear of lenticule (1 eye), epithelial implantation (4 eyes), transitory glaucoma (1 eye), irregular astigmatism (7 eyes), and undercorrection (24 eyes). Four of the latter underwent radial keratotomy. Refract Corneal Surg 1991;7:223-231.)