Mooren's ulcer has not yet been treated successfully with drugs. Cautery, cryocoagulation, surgical diathermy, lamellar or perforating keratoplasty, and conjunctivoplasty usually have no or only little success. We have been able to cure our last five cases of Mooren's ulcer by an extensive and deep thermocoagulation both of the ulcer, the swollen corneal margins and the bordering conjunctiva. Then followed dilatation of the conjunctival vessels with Dionine and Priscol ointments.