So far, no investigations of micromorphological changes in the human cornea after in situ keratomileusis have been published. In 10 eyes of five patients who had undergone in situ keratomileusis, wound healing processes were followed up with a newly developed confocal slit-scanning video-microscope. Post-operatively, alterations in the corneal endothelium and in the corneal stroma were found. Wide streaky distortions were observed within the stroma above and below the lamellar incision during the early days immediately after surgery. These distortions were probably induced by shearing stresses of the oscillating blade of the microkeratome. Small scattering centers were seen at the level of the lamellar incision, which are thought to reflect a very slight roughness of the interface. In the immediate postoperative period the corneal endothelium showed reversible inhomogeneitis similar to blebs after short-term contact lens wearing, which are thought to be due to a hypoxia during the surgery. The endothelial alterations and the streaky distortions within the stroma disappeared within 9 days after the surgery whereas the scattering centers regressed much more slowly and could still be observed 60 days after the surgery. The total amount of scattered light of the cornea, however, was not increased except in one patient. The results show that outside the level of the lamellar incision, in situ keratomileusis leads to only short-term alterations of the corneal micromorphology, and that confocal in vivo slit-scanning video-microscopy allows thorough examination of these alterations.