'Snailtracks' (grey-white streaks and patches on the posterior corneal surface which occur postoperatively) have recently been implicated as possible markers of corneal endothelial cell damage. We have examined this phenomenon in vivo with the slit-lamp and specular microscope. We recognised three types of linear form and, in contradiction of other observers, found that each was always coincident with a wrinkle in Descemet's membrane. Moreover, we were able to demonstrate only minimal endothelial cell damage in only a few of the tracks.