AIM: To check whether myopic laser in situ kerato- mileusis(LASIK) induces changes on the posterior corneal surface. METHODS: Orbscan-Ⅱz and Pentacam were used to measure preoperative and postoperative posterior corneal topography in 66 eyes (of 66 subjects) that had undergone standard myopic LASIK surgery. Changes in the posterior corneal elevation, and anterior chamber depth were compared using the paired sample t test. RESULTS: Measured with Orbscan-Ⅱz, significant forward shifting of the central posterior corneal surface was found after LASIK (P=0.000), while measured with Pentacam, no significant difference in posterior corneal displacement was found (P＞0.05). Preoperative refraction (r=-0.403,P=0.001), central corneal thickness (r=-0.349, P=0.004), ablation depth (r=0.411, P=0.001) were significantly correlated with the posterior corneal displacement measured with Orbscan-Ⅱz. CONCLUSION: No forward shifting of the central posterior corneal surface occurred after LASIK. Orbscan-Ⅱz was affected by the magnification effect of corneas after LASIK, when it was used to measure the posterior corneal surface.