This chapter describes various preoperative, operative and postoperative LASIK complications in detail. The preoperative LASIK complications include red light, yellow light and green light. The LASIK operative complications include use of machines, excimer laser, flap maker (microkeratome) and femtosecond laser flaps. The LASIK postoperative complications include overcorrection/undercorrection, epithelial ingrowth, foreign bodies beneath flaps, dislodged flap, microstriae, postoperative inflammation (central toxic keratopathy, pressure-induced stromal keratitis and dry eyes), infection, glare/halo and ectasias. Avoiding complications in LASIK surgery may be impossible but developing a risk avoidance system along with a good history and physical examination may help. Part of avoiding complications involves a basic and sometimes detailed understanding of all machinery used in the LASIK surgery process.