Of a series of 263 patients undergoing allogeneic bone marrow transplantation (BMT), 24 patients developed conjunctival involvement by graft-vs-host disease (GVHD). In each case, a distinct-appearing conjunctivitis developed that representing GVHD of the conjunctiva. In 19 cases (79%), conjunctival GVHD presented with pseudomembrane formation due to loss of the conjunctival epithelium; in 4 of these cases, the corneal epithelium was lost as well. Nineteen patients developed this feature in association with acute GVHD, and mortality among these patients was 89.5%. Kaplan-Meier analysis of survival demonstrated a decreased survival of patients with conjunctival involvement compared with all marrow transplant recipients and compared with all patients with GVHD. However, survival was similar to that seen in patients with severe systemic GVHD (overall stages II through IV). Five patients developed conjunctival GVHD in association with chronic GVHD, and all had severe chronic GVHD. four of these five with chronic GVHD subsequently died. Conjunctival involvement by GVHD represents a distinct clinical finding and is a marker for severe systemic involvement by GVHD. A clinical staging system for ocular involvement was formulated.