Three years and 5 months after uneventful laser in situ keratomileusis, the left eye of a 39-year-old man was struck by the finger of a friend while the two were practicing karate, resulting in loss of the flap. The patient had performed this contact sport regularly for years. When last seen 16 weeks after injury, the best corrected visual acuity in the left eye was 20/40 with -1.75 -0.50x30. Mild central corneal haze was observed under slitlamp examination, the flap was missing, and the patient complained of dysphotopsia. Pachymetry in the left eye was 394 mum, with an irregular corneal contour. Flap loss is a serious complication because severe irregular astigmatism and unpredictable refractive change can occur. This case highlights the vulnerability of flaps to trauma even late postoperatively.