We describe 6 bilateral cases of progressive Mooren's ulcer treated by performing conjunctival excision (regional or 360 degrees peritomy). The histopathological study of the conjunctiva adjacent to the lesion showed an hyperaemic and edematous stroma infiltrated mainly by plasma cells and lymphocytes without signs of vasculitis. The peripheral portion of the ulcer was characterized by necrobiotic and hemorrhagic elements along with an absence of the overlying epithelium and Bowman's membrane. Inflammation of the corneal stroma was present in the peripheral but absent in the central edge of the ulcer, a characteristic sign of a rodent ulcer. Therefore, the histopathological study was very useful for the final diagnosis and the differential diagnosis of Mooren's ulcer from other cases of peripheral ulcerative keratitis. In all 6 cases conjunctival excision appeared to be an effective procedure in halting the progression of the disease: absence of recurrences during a follow-up period of 1-2 years provided an essential healing of the cornea.