In 37 eyes of 23 patients with Mooren's ulcer initial treatment with topical corticosteroids healed 12 ulcers. Conjunctival excision, used if the corticosteroids failed, healed eight ulcers. Patients failing to respond to topical corticosteroids and conjunctival excision were treated with immunosuppression. This resulted in healing of four of 13 ulcers. Overall, 24 of 37 ulcers (65%) were healed. Eight of nine unilateral ulcers and six of six bilateral nonsimultaneous ulcers (ulcer began in one eye after healing in the other) healed after treatment with topical corticosteroids and conjunctival excision. However, only ten of 22 bilateral simultaneous ulcers responded to topical corticosteroids, conjunctival excision, and immunosuppression. Bilateral, simultaneously active Mooren's ulcer is a severe, relentlessly destructive condition for which no completely satisfactory treatment exists.